Last list item
Last list item is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
- Task
List = [6, 81, 243, 14, 25, 49, 123, 69, 11]
Find the two smallest items, remove them from the list, find their sum, and add the sum to the end of list.
Repeat until the list contains one element.
Show the steps and last item on this page.
Show the unsorted list in output in case "Without sort"
F add_least_reduce(&lis)
L lis.len > 1
V el1 = lis.pop(lis.index(min(lis)))
V el2 = lis.pop(lis.index(min(lis)))
lis.append(el1 + el2)
print(‘Interim list: ’lis)
R lis
V LIST = [6, 81, 243, 14, 25, 49, 123, 69, 11]
print(LIST‘ ==> ’add_least_reduce(©(LIST)))- Output:
Interim list: [81, 243, 14, 25, 49, 123, 69, 17] Interim list: [81, 243, 25, 49, 123, 69, 31] Interim list: [81, 243, 49, 123, 69, 56] Interim list: [81, 243, 123, 69, 105] Interim list: [243, 123, 105, 150] Interim list: [243, 150, 228] Interim list: [243, 378] Interim list: [621] [6, 81, 243, 14, 25, 49, 123, 69, 11] ==> [621]
With sorting
with Ada.Text_IO;
with Ada.Containers.Vectors;
procedure Last_List_Item_Sorted is
package Integer_IO is new Ada.Text_IO.Integer_IO (Integer);
package Vectors is
new Ada.Containers.Vectors (Index_Type => Positive,
Element_Type => Integer);
package Vector_Sorting is
new Vectors.Generic_Sorting;
use Ada.Containers, Vectors, Ada.Text_IO, Integer_IO;
procedure Put (List : Vector) is
begin
Put ("[");
for V of List loop
Put (" "); Put (V, Width => 0);
end loop;
Put ("]");
end Put;
List : Vector := 6 & 81 & 243 & 14 & 25 & 49 & 123 & 69 & 11;
begin
Default_Width := 0;
while List.Length >= 2 loop
Vector_Sorting.Sort (List);
Put (List);
declare
Small_1 : constant Integer := List (List.First_Index + 0);
Small_2 : constant Integer := List (List.First_Index + 1);
Sum : constant Integer := Small_1 + Small_2;
begin
List.Delete_First (2);
Put (". Smallest: "); Put (Small_1); Put (" and "); Put (Small_2);
Put (". Sum: "); Put (Sum); New_Line;
List.Append (Sum);
end;
end loop;
Put (List); New_Line;
end Last_List_Item_Sorted;
- Output:
[ 6 11 14 25 49 69 81 123 243]. Smallest: 6 and 11. Sum: 17 [ 14 17 25 49 69 81 123 243]. Smallest: 14 and 17. Sum: 31 [ 25 31 49 69 81 123 243]. Smallest: 25 and 31. Sum: 56 [ 49 56 69 81 123 243]. Smallest: 49 and 56. Sum: 105 [ 69 81 105 123 243]. Smallest: 69 and 81. Sum: 150 [ 105 123 150 243]. Smallest: 105 and 123. Sum: 228 [ 150 228 243]. Smallest: 150 and 228. Sum: 378 [ 243 378]. Smallest: 243 and 378. Sum: 621 [ 621]
Without sorting
with Ada.Text_IO;
with Ada.Containers.Vectors;
procedure Last_List_Item is
package Integer_IO is new Ada.Text_IO.Integer_IO (Integer);
package Element_Vectors is
new Ada.Containers.Vectors (Index_Type => Positive,
Element_Type => Integer);
use Ada.Containers, Element_Vectors, Ada.Text_IO, Integer_IO;
function Pick_Smallest (List : in out Vector) return Integer is
Value : Integer := Integer'Last;
begin
if List.Is_Empty then
raise Constraint_Error;
end if;
for V of List loop
Value := Integer'Min (Value, V);
end loop;
List.Delete (List.Find_Index (Value));
return Value;
end Pick_Smallest;
procedure Put (List : Vector) is
begin
Put ("[");
for V of List loop
Put (" "); Put (V, Width => 0);
end loop;
Put ("]");
end Put;
List : Vector := 6 & 81 & 243 & 14 & 25 & 49 & 123 & 69 & 11;
begin
Default_Width := 0;
while List.Length >= 2 loop
Put (List); Put (". Smallest: ");
declare
Small_1 : constant Integer := Pick_Smallest (List);
Small_2 : constant Integer := Pick_Smallest (List);
Sum : constant Integer := Small_1 + Small_2;
begin
Put (Small_1); Put (" and "); Put (Small_2);
Put (". Sum: "); Put (Sum); New_Line;
List.Append (Sum);
end;
end loop;
Put (List); New_Line;
end Last_List_Item;
- Output:
[ 6 81 243 14 25 49 123 69 11]. Smallest: 6 and 11. Sum: 17 [ 81 243 14 25 49 123 69 17]. Smallest: 14 and 17. Sum: 31 [ 81 243 25 49 123 69 31]. Smallest: 25 and 31. Sum: 56 [ 81 243 49 123 69 56]. Smallest: 49 and 56. Sum: 105 [ 81 243 123 69 105]. Smallest: 69 and 81. Sum: 150 [ 243 123 105 150]. Smallest: 105 and 123. Sum: 228 [ 243 150 228]. Smallest: 150 and 228. Sum: 378 [ 243 378]. Smallest: 243 and 378. Sum: 621 [ 621]
With sorting
Note the RC ALGOL 68 sort library is on a separate page on Rosetta Code - see the above link.
BEGIN # find the last element after repeatedely adding the sum of the #
# two smallest elements and removing them #
PR read "sort.incl.a68" PR # row sorting utilities #
[ 1 : 9 ]INT a := ( 6, 81, 243, 14, 25, 49, 123, 69, 11 );
INT a count := UPB a;
WHILE a count > 1 DO
a QUICKSORT ELEMENTS( LWB a, a count );
print( ( "Sorted list:" ) );FOR i TO a count DO print( ( " ", whole( a[ i ], 0 ) ) ) OD;
INT sum = a[ 1 ] + a[ 2 ];
print( ( "; two smallest: " , whole( a[ 1 ], 0 )
, " + ", whole( a[ 2 ], 0 )
, " = ", whole( sum, 0 )
, newline
)
);
a[ 1 : a count - 2 ] := a[ 3 : a count ];
a count -:= 1 ;
a[ a count ] := sum
OD;
print( ( "Last item is ", whole( a[ 1 ], 0 ), ".", newline ) )
END- Output:
Sorted list: 6 11 14 25 49 69 81 123 243; two smallest: 6 + 11 = 17 Sorted list: 14 17 25 49 69 81 123 243; two smallest: 14 + 17 = 31 Sorted list: 25 31 49 69 81 123 243; two smallest: 25 + 31 = 56 Sorted list: 49 56 69 81 123 243; two smallest: 49 + 56 = 105 Sorted list: 69 81 105 123 243; two smallest: 69 + 81 = 150 Sorted list: 105 123 150 243; two smallest: 105 + 123 = 228 Sorted list: 150 228 243; two smallest: 150 + 228 = 378 Sorted list: 243 378; two smallest: 243 + 378 = 621 Last item is 621.
Without sorting
Translation of the sorted Wren version with the sorting removed.
BEGIN # find the last element after repeatedly adding the sum #
# of the two smallest elements and removing them #
[ 1 : 9 ]INT a := ( 6, 81, 243, 14, 25, 49, 123, 69, 11 );
INT a count := UPB a;
WHILE a count > 1 DO
print( ( "List:" ) );FOR i TO a count DO print( ( " ", whole( a[ i ], 0 ) ) ) OD;
INT s1pos, s2pos;
IF a[ 1 ] < a[ 2 ]
THEN s1pos := 1; s2pos := 2
ELSE s1pos := 2; s2pos := 1
FI;
FOR i FROM 3 TO a count DO
IF a[ i ] < a[ s1pos ] THEN s2pos := s1pos; s1pos := i
ELIF a[ i ] < a[ s2pos ] THEN s2pos := i
FI
OD;
INT sum = a[ s1pos ] + a[ s2pos ];
print( ( "; two smallest: " , whole( a[ s1pos ], 0 ), " @ ", whole( s1pos, 0 )
, " and ", whole( a[ s2pos ], 0 ), " @ ", whole( s2pos, 0 )
, "; sum = ", whole( sum, 0 )
, newline
)
);
INT m pos := 0;
FOR i TO a count DO
IF i /= s1pos AND i /= s2pos THEN a[ m pos +:= 1 ] := a[ i ] FI
OD;
a[ m pos + 1 ] := sum;
a count -:= 1
OD;
print( ( "Last item is ", whole( a[ 1 ], 0 ), ".", newline ) )
END- Output:
List: 6 81 243 14 25 49 123 69 11; two smallest: 6 @ 1 and 11 @ 9; sum = 17 List: 81 243 14 25 49 123 69 17; two smallest: 14 @ 3 and 17 @ 8; sum = 31 List: 81 243 25 49 123 69 31; two smallest: 25 @ 3 and 31 @ 7; sum = 56 List: 81 243 49 123 69 56; two smallest: 49 @ 3 and 56 @ 6; sum = 105 List: 81 243 123 69 105; two smallest: 69 @ 4 and 81 @ 1; sum = 150 List: 243 123 105 150; two smallest: 105 @ 3 and 123 @ 2; sum = 228 List: 243 150 228; two smallest: 150 @ 2 and 228 @ 3; sum = 378 List: 243 378; two smallest: 243 @ 1 and 378 @ 2; sum = 621 Last item is 621.
100 DATA 6, 81, 243, 14, 25, 49, 123, 69, 11
110 FOR L = 0 TO 8
120 READ L(L)
130 NEXT
140 LET L = L - 1
150 GOSUB 180"LAST LIST ITEM"
160 GOSUB 250"PRINT LIST"
170 END
180 IF L = 0 THEN RETURN
190 FOR L = L TO 0 STEP 0
200 GOSUB 340"FIND THE 2 SMALLEST"
210 LET L = L + 1
220 LET L(L) = PREVIOUSSMALLEST + SMALLEST
230 NEXT L
240 RETURN
250 PRINT
260 LET H = 1
270 FOR I = 0 TO L
280 IF NOT H(I) THEN H(I) = H
290 LET H = H(I) + LEN ( STR$ (L(I))) + 1
300 HTAB H(I)
310 PRINT L(I)" ";
320 NEXT I
330 RETURN
340 GOSUB 250"PRINT LIST"
350 GOSUB 370"FIND SMALLEST"
360 LET PREVIOUSSMALLEST = SMALLEST
370 LET S = 0
380 FOR I = 0 TO L
390 LET SMALLEST = L(S)
400 IF L(I) < SMALLEST THEN S = I
410 NEXT I
420 LET SMALLEST = L(S)
430 LET L = L - 1
440 IF S > L THEN RETURN
450 FOR I = S TO L
460 LET L(I) = L(I + 1)
470 LET H(I) = H(I + 1)
480 NEXT I
490 RETURN
- Output:
6 81 243 14 25 49 123 69 11
81 243 14 25 49 123 69 17
81 243 25 49 123 69 31
81 243 49 123 69 56
81 243 123 69 105
243 123 105 150
243 150 228
243 378
621
on lastListItem(lst)
set astid to AppleScript's text item delimiters
set AppleScript's text item delimiters to ", "
set output to {"Steps:", "{" & lst & "} ← Original"}
set len to (count lst)
if (len > 1) then
repeat with len from len to 3 by -1
set {i, j} to {1, 2}
set {s1, s2} to lst
if (s2 < s1) then set {i, s1, j, s2} to {j, s2, i, s1}
repeat with k from 3 to len
set v to lst's item k
if (v < s1) then
set {i, s1, j, s2} to {k, v, i, s1}
else if (v < s2) then
set {j, s2} to {k, v}
end if
end repeat
tell lst to set {item i, item j} to {missing value, missing value}
set lst to lst's numbers
set lst's end to s1 + s2
set output's end to "{" & lst & "} ← " & s1 & " + " & s2 & " = " & result
end repeat
tell lst to set end of output to "{" & (beginning + end) & "} ← " & beginning & " + " & end & " = " & (beginning + end)
end if
set AppleScript's text item delimiters to linefeed
set output to output as text
set AppleScript's text item delimiters to astid
return output
end lastListItem
lastListItem({6, 81, 243, 14, 25, 49, 123, 69, 11})
- Output:
"Steps:
{6, 81, 243, 14, 25, 49, 123, 69, 11} ← Original
{81, 243, 14, 25, 49, 123, 69, 17} ← 6 + 11 = 17
{81, 243, 25, 49, 123, 69, 31} ← 14 + 17 = 31
{81, 243, 49, 123, 69, 56} ← 25 + 31 = 56
{81, 243, 123, 69, 105} ← 49 + 56 = 105
{243, 123, 105, 150} ← 69 + 81 = 150
{243, 150, 228} ← 105 + 123 = 228
{243, 378} ← 150 + 228 = 378
{621} ← 243 + 378 = 621"
lst: [6 81 243 14 25 49 123 69 11]
initial: lst
while [1 < size lst][
remove 'lst min1: <= min lst
remove 'lst min2: <= min lst
append 'lst min1 + min2
print ["List:" lst]
]
print ""
print [initial "=>" lst]
- Output:
List: [81 243 14 25 49 123 69 17] List: [81 243 25 49 123 69 31] List: [81 243 49 123 69 56] List: [81 243 123 69 105] List: [243 123 105 150] List: [243 150 228] List: [243 378] List: [621] [6 81 243 14 25 49 123 69 11] => [621]
List := [6, 81, 243, 14, 25, 49, 123, 69, 11]
steps := "Initial List `t`t`t" List2str(List) "`n"
while List.Count() > 1
{
sum := 0, str := ""
loop 2
{
num := min(List*)
sum += num
removeFromList(List, num)
str .= (!str ? "2 smallest numbers: " : " + ") num
}
List.Push(sum)
steps .= str " = " sum "`t" List2str(List) "`n"
}
MsgBox % result := steps
return
removeFromList(ByRef List, num){
for i, v in List
if (v = num)
{
List.RemoveAt(i)
break
}
}
List2str(List){
for i, v in List
unsorted_List .= v ", "
return "[" Trim(unsorted_List, ", ") "]"
}
- Output:
Initial List [6, 81, 243, 14, 25, 49, 123, 69, 11] 2 smallest numbers: 6 + 11 = 17 [81, 243, 14, 25, 49, 123, 69, 17] 2 smallest numbers: 14 + 17 = 31 [81, 243, 25, 49, 123, 69, 31] 2 smallest numbers: 25 + 31 = 56 [81, 243, 49, 123, 69, 56] 2 smallest numbers: 49 + 56 = 105 [81, 243, 123, 69, 105] 2 smallest numbers: 69 + 81 = 150 [243, 123, 105, 150] 2 smallest numbers: 105 + 123 = 228 [243, 150, 228] 2 smallest numbers: 150 + 228 = 378 [243, 378] 2 smallest numbers: 243 + 378 = 621 [621]
# syntax: GAWK -f LAST_LIST_ITEM.AWK
BEGIN {
split("6,81,243,14,25,49,123,69,11",arr1,",")
PROCINFO["sorted_in"] = "@val_num_asc"
while (length(arr1) > 1) {
for (i in arr1) { printf("%s ",arr1[i]) } # show sorted list
j = 0
delete arr2
for (i in arr1) { arr2[++j] = arr1[i] } # copy arr1 into arr2
sum = arr2[1] + arr2[2]
printf(": %s+%s=%s\n",arr2[1],arr2[2],sum)
delete arr2[2]
arr2[1] = sum
delete arr1
for (i in arr2) { arr1[i] = arr2[i] } # copy arr2 into arr1
}
printf("sum=%d\n",sum)
exit(0)
}
- Output:
6 11 14 25 49 69 81 123 243 : 6+11=17 14 17 25 49 69 81 123 243 : 14+17=31 25 31 49 69 81 123 243 : 25+31=56 49 56 69 81 123 243 : 49+56=105 69 81 105 123 243 : 69+81=150 105 123 150 243 : 105+123=228 150 228 243 : 150+228=378 243 378 : 243+378=621 sum=621
With and without sorting
list ← ⟨6, 81, 243, 14, 25, 49, 123, 69, 11⟩
W_sort ← {{i←2↑∧𝕩, (𝕩/˜¬𝕩∊i)∾+´i}⍟(↕≠𝕩)𝕩}
WO_sort ← {{m←⌊´𝕩, n←⌊´𝕩/˜¬m=𝕩, (𝕩/˜¬𝕩∊m‿n)∾m+n}⍟(↕≠𝕩)𝕩}
•Show¨W_sort list
•Show¨WO_sort list
⟨ 6 81 243 14 25 49 123 69 11 ⟩
⟨ 81 243 14 25 49 123 69 17 ⟩
⟨ 81 243 25 49 123 69 31 ⟩
⟨ 81 243 49 123 69 56 ⟩
⟨ 81 243 123 69 105 ⟩
⟨ 243 123 105 150 ⟩
⟨ 243 150 228 ⟩
⟨ 243 378 ⟩
⟨ 621 ⟩
⟨ 6 81 243 14 25 49 123 69 11 ⟩
⟨ 81 243 14 25 49 123 69 17 ⟩
⟨ 81 243 25 49 123 69 31 ⟩
⟨ 81 243 49 123 69 56 ⟩
⟨ 81 243 123 69 105 ⟩
⟨ 243 123 105 150 ⟩
⟨ 243 150 228 ⟩
⟨ 243 378 ⟩
⟨ 621 ⟩
With sorting
#include <stdio.h>
#include <stdlib.h>
int compare(const void *a, const void *b) {
int aa = *(const int *)a;
int bb = *(const int *)b;
if (aa < bb) return -1;
if (aa > bb) return 1;
return 0;
}
int main() {
int a[] = {6, 81, 243, 14, 25, 49, 123, 69, 11};
int isize = sizeof(int);
int asize = sizeof(a) / isize;
int i, sum;
while (asize > 1) {
qsort(a, asize, isize, compare);
printf("Sorted list: ");
for (i = 0; i < asize; ++i) printf("%d ", a[i]);
printf("\n");
sum = a[0] + a[1];
printf("Two smallest: %d + %d = %d\n", a[0], a[1], sum);
for (i = 2; i < asize; ++i) a[i-2] = a[i];
a[asize - 2] = sum;
asize--;
}
printf("Last item is %d.\n", a[0]);
return 0;
}
- Output:
Sorted list: 6 11 14 25 49 69 81 123 243 Two smallest: 6 + 11 = 17 Sorted list: 14 17 25 49 69 81 123 243 Two smallest: 14 + 17 = 31 Sorted list: 25 31 49 69 81 123 243 Two smallest: 25 + 31 = 56 Sorted list: 49 56 69 81 123 243 Two smallest: 49 + 56 = 105 Sorted list: 69 81 105 123 243 Two smallest: 69 + 81 = 150 Sorted list: 105 123 150 243 Two smallest: 105 + 123 = 228 Sorted list: 150 228 243 Two smallest: 150 + 228 = 378 Sorted list: 243 378 Two smallest: 243 + 378 = 621 Last item is 621.
Without sorting
#include <stdio.h>
int findMin(int a[], int asize, int *pmin) {
int i, ix = 0;
*pmin = a[0];
for (i = 0; i < asize; ++i) {
if (a[i] < *pmin) {
ix = i;
*pmin = a[i];
}
}
return ix;
}
int main() {
int a[] = {6, 81, 243, 14, 25, 49, 123, 69, 11};
int isize = sizeof(int);
int asize = sizeof(a) / isize;
int i, j, sum, ix, min = 0, s[2];
while (asize > 1) {
printf("List: ");
for (i = 0; i < asize; ++i) printf("%d ", a[i]);
printf("\n");
for (i = 0; i < 2; ++i) {
ix = findMin(a, asize, &min);
s[i] = min;
for (j = ix+1; j < asize; ++j) a[j-1] = a[j];
asize--;
}
sum = s[0] + s[1];
printf("Two smallest: %d + %d = %d\n", s[0], s[1], sum);
a[asize] = sum;
asize++;
}
printf("Last item is %d.\n", a[0]);
return 0;
}
- Output:
List: 6 81 243 14 25 49 123 69 11 Two smallest: 6 + 11 = 17 List: 81 243 14 25 49 123 69 17 Two smallest: 14 + 17 = 31 List: 81 243 25 49 123 69 31 Two smallest: 25 + 31 = 56 List: 81 243 49 123 69 56 Two smallest: 49 + 56 = 105 List: 81 243 123 69 105 Two smallest: 69 + 81 = 150 List: 243 123 105 150 Two smallest: 105 + 123 = 228 List: 243 150 228 Two smallest: 150 + 228 = 378 List: 243 378 Two smallest: 243 + 378 = 621 Last item is 621.
#include <iostream>
#include <list>
using namespace std;
void PrintContainer(const auto& container)
{
cout << "[ ";
for_each(container.begin(), container.end(), [](auto item){cout << item << " ";});
cout << "]";
}
int main()
{
list<int> numbers{6, 81, 243, 14, 25, 49, 123, 69, 11};
// a lambda to remove the minimum item
auto removeMin = [](auto& container)
{
auto minIterator = min_element(container.begin(), container.end());
auto minValue = *minIterator;
container.erase(minIterator);
return minValue;
};
while(numbers.size() > 1)
{
PrintContainer(numbers);
auto minValue = removeMin(numbers);
auto nextMinValue = removeMin(numbers);
auto sum = minValue + nextMinValue;
numbers.push_back(sum);
cout << " => " << minValue << " + " << nextMinValue << " = " << sum << "\n";
}
cout << "Final list: "; PrintContainer(numbers); cout << "\n";
}
- Output:
[ 6 81 243 14 25 49 123 69 11 ] => 6 + 11 = 17 [ 81 243 14 25 49 123 69 17 ] => 14 + 17 = 31 [ 81 243 25 49 123 69 31 ] => 25 + 31 = 56 [ 81 243 49 123 69 56 ] => 49 + 56 = 105 [ 81 243 123 69 105 ] => 69 + 81 = 150 [ 243 123 105 150 ] => 105 + 123 = 228 [ 243 150 228 ] => 150 + 228 = 378 [ 243 378 ] => 243 + 378 = 621 Final list: [ 621 ]
Copied almost verbatim from Ruby, with minimal syntax changes.
p original = [6, 81, 243, 14, 25, 49, 123, 69, 11]
until original.size == 1
mins = original.min(2)
mins.each{|el| original.delete_at(original.index!(el)) }
p original << mins.sum
end
- Output:
Same as Ruby's.
Uses standard Delphi object "TList" to manipulate the array.
procedure FindSmallest(LS: TList; var Index,Value: Integer);
{Find smallest value in LIst}
var I: integer;
begin
Value:=High(integer);
for I:=0 to LS.Count-1 do
if integer(LS[I])<Value then
begin
Value:=integer(LS[I]);
Index:=I;
end;
end;
procedure ShowArray(Memo: TMemo; LS: TList);
{Display the contents of specified array}
var I: integer;
var S: string;
begin
S:='[';
for I:=0 to LS.Count-1 do
begin
if I>0 then S:=S+' ';
S:=S+IntToStr(Integer(LS[I]));
end;
S:=S+']';
Memo.Lines.Add(S);
end;
procedure LastItem(Memo: TMemo; IA: array of integer);
{Repeatedly remove the two lowest values}
{Add them together and add to the list}
var LS: TList;
var I,Inx,Val1,Val2: integer;
begin
LS:=TList.Create;
try
for I:=0 to High(IA) do LS.Add(Pointer(IA[I]));
while LS.Count>1 do
begin
ShowArray(Memo,LS);
FindSmallest(LS,Inx,Val1);
LS.Delete(Inx);
FindSmallest(LS,Inx,Val2);
LS.Delete(Inx);
LS.Add(Pointer(Val1 + Val2))
end;
Memo.Lines.Add(IntToStr(integer(LS[0])));
finally LS.Free; end;
end;
{Supplied test array}
const IntArray: array [0..8] of integer=(6, 81, 243, 14, 25, 49, 123, 69, 11);
procedure DoLastItem(Memo: TMemo);
{Do last item problem}
begin
LastItem(Memo,IntArray);
end;
- Output:
[6 81 243 14 25 49 123 69 11] [81 243 14 25 49 123 69 17] [81 243 25 49 123 69 31] [81 243 49 123 69 56] [81 243 123 69 105] [243 123 105 150] [243 150 228] [243 378] 621
l[] = [ 6 81 243 14 25 49 123 69 11 ]
while len l[] > 1
sum = 0
for k to 2
for i to len l[] - 1
if l[i] < l[$]
swap l[i] l[$]
.
.
sum += l[$]
len l[] -1
.
l[] &= sum
print l[]
.
- Output:
[ 69 81 243 14 25 49 123 17 ] [ 123 81 243 69 25 49 31 ] [ 123 81 243 69 49 56 ] [ 123 81 243 69 105 ] [ 123 105 243 150 ] [ 243 150 228 ] [ 243 378 ] [ 621 ]
USING: formatting io kernel math math.statistics prettyprint
sequences sequences.extras ;
: list. ( seq -- )
"List: " write [ bl ] [ pprint ] interleave nl ;
: smallest. ( seq -- )
first2 2dup + "Two smallest: %d + %d = %d\n" printf ;
: remove-all-first! ( seq elts -- seq' )
[ swap remove-first! ] each ;
: step ( seq -- seq' )
dup { 0 1 } kth-smallests tuck remove-all-first! over
smallest. swap sum suffix! ;
V{ 6 81 243 14 25 49 123 69 11 }
[ dup length 1 > ] [ dup list. step ] while
last "Last item is %d.\n" printf
- Output:
List: 6 81 243 14 25 49 123 69 11 Two smallest: 6 + 11 = 17 List: 81 243 14 25 49 123 69 17 Two smallest: 14 + 17 = 31 List: 81 243 25 49 123 69 31 Two smallest: 25 + 31 = 56 List: 81 243 49 123 69 56 Two smallest: 49 + 56 = 105 List: 81 243 123 69 105 Two smallest: 69 + 81 = 150 List: 243 123 105 150 Two smallest: 105 + 123 = 228 List: 243 150 228 Two smallest: 150 + 228 = 378 List: 243 378 Two smallest: 243 + 378 = 621 Last item is 621.
#define HUGE 99999999
redim as integer list(0 to 8)
list(0) = 6 :list(1) = 81:list(2) = 243:list(3) = 14:list(4) = 25:list(5) = 49:list(6) = 123:list(7) = 69:list(8) = 11
dim as integer s, si, ss, ssi, i
for i = 0 to ubound(list)
print list(i);" ";
next i
print
while ubound(list) > 0
s = HUGE
ss = HUGE
for i = 0 to ubound(list)
if list(i)<s then
ss = s
ssi = si
s = list(i)
si = i
elseif list(i)<ss then
ss = list(i)
ssi = i
end if
next i
if ss<s then swap s, ss
for i = si to ubound(list)-1
list(i) = list(i+1)
next i
for i = ssi to ubound(list)-2
list(i) = list(i+1)
next i
list(ubound(list)-1) = s+ss
redim preserve list(0 to ubound(list)-1)
for i = 0 to ubound(list)
print list(i);" ";
next i
print
wend
- Output:
6 81 243 14 25 49 123 69 11 81 243 14 25 49 123 69 17 81 243 25 49 123 69 31 81 243 49 123 69 56 81 243 123 69 105 243 123 105 150 243 150 228 243 378 621
local fn LastListItem( array as CFArrayRef ) as int
int result
CFMutableArrayRef list = fn MutableArrayWithArray( array )
SortDescriptorRef sortAscending = fn SortDescriptorWithKey( NULL, YES )
MutableArraySortUsingDescriptors( list, @[sortAscending] )
while ( len(list) > 1 )
printf @"%@", fn ArrayComponentsJoinedByString( list, @"\t" )
result = fn NumberIntValue( list[0] ) + fn NumberIntValue( list[1] )
MutableArrayInsertObjectAtIndex( list, fn NumberWithInt( result ), len(list) - 1 )
MutableArrayRemoveObjectAtIndex( list, 0 )
MutableArrayRemoveObjectAtIndex( list, 0 )
MutableArraySortUsingDescriptors( list, @[sortAscending] )
wend
end fn = result
CFArrayRef list : list = @[@6, @81, @243, @14, @25, @49, @123, @69, @11]
printf @"%@ — Original task list", fn ArrayComponentsJoinedByString( list, @"\t" )
print fn LastListItem( list )
HandleEvents- Output:
6 81 243 14 25 49 123 69 11 — Original task list 6 11 14 25 49 69 81 123 243 14 17 25 49 69 81 123 243 25 31 49 69 81 123 243 49 56 69 81 123 243 69 81 105 123 243 105 123 150 243 150 228 243 243 378 621
With sorting
package main
import (
"fmt"
"sort"
)
func main() {
a := []int{6, 81, 243, 14, 25, 49, 123, 69, 11}
for len(a) > 1 {
sort.Ints(a)
fmt.Println("Sorted list:", a)
sum := a[0] + a[1]
fmt.Printf("Two smallest: %d + %d = %d\n", a[0], a[1], sum)
a = append(a, sum)
a = a[2:]
}
fmt.Println("Last item is", a[0], "\b.")
}
- Output:
Sorted list: [6 11 14 25 49 69 81 123 243] Two smallest: 6 + 11 = 17 Sorted list: [14 17 25 49 69 81 123 243] Two smallest: 14 + 17 = 31 Sorted list: [25 31 49 69 81 123 243] Two smallest: 25 + 31 = 56 Sorted list: [49 56 69 81 123 243] Two smallest: 49 + 56 = 105 Sorted list: [69 81 105 123 243] Two smallest: 69 + 81 = 150 Sorted list: [105 123 150 243] Two smallest: 105 + 123 = 228 Sorted list: [150 228 243] Two smallest: 150 + 228 = 378 Sorted list: [243 378] Two smallest: 243 + 378 = 621 Last item is 621.
Without sorting
package main
import "fmt"
func findMin(a []int) (int, int) {
ix := 0
min := a[0]
for i := 1; i < len(a); i++ {
if a[i] < min {
ix = i
min = a[i]
}
}
return min, ix
}
func main() {
a := []int{6, 81, 243, 14, 25, 49, 123, 69, 11}
for len(a) > 1 {
fmt.Println("List:", a)
var s [2]int
for i := 0; i < 2; i++ {
min, ix := findMin(a)
s[i] = min
a = append(a[:ix], a[ix+1:]...)
}
sum := s[0] + s[1]
fmt.Printf("Two smallest: %d + %d = %d\n", s[0], s[1], sum)
a = append(a, sum)
}
fmt.Println("Last item is", a[0], "\b.")
}
- Output:
List: [6 81 243 14 25 49 123 69 11] Two smallest: 6 + 11 = 17 List: [81 243 14 25 49 123 69 17] Two smallest: 14 + 17 = 31 List: [81 243 25 49 123 69 31] Two smallest: 25 + 31 = 56 List: [81 243 49 123 69 56] Two smallest: 49 + 56 = 105 List: [81 243 123 69 105] Two smallest: 69 + 81 = 150 List: [243 123 105 150] Two smallest: 105 + 123 = 228 List: [243 150 228] Two smallest: 150 + 228 = 378 List: [243 378] Two smallest: 243 + 378 = 621 Last item is 621.
Here we maintain the unsorted order in the intermediate steps:
rplc&(' 0';'')"1": ((-. , +/@]) 2 {. /:~)^:a: 81 243 14 25 49 123 69 17
81 243 14 25 49 123 69 17
81 243 25 49 123 69 31
81 243 49 123 69 56
81 243 123 69 105
243 123 105 150
243 150 228
243 378
621
Alternative interpretation:
([[:echo,:#~1<#)@((-. , +/@]) 2 {. /:~)^:_] 81 243 14 25 49 123 69 17
81 243 25 49 123 69 31
81 243 49 123 69 56
81 243 123 69 105
243 123 105 150
243 150 228
243 378
621
import java.util.ArrayList;
import java.util.List;
public final class LastListItem {
public static void main(String[] args) {
List<Integer> numbers = new ArrayList<Integer>(List.of( 6, 81, 243, 14, 25, 49, 123, 69, 11 ) );
while ( numbers.size() > 1 ) {
System.out.print(numbers);
final int minValueFirst = numbers.stream().mapToInt( i -> i ).min().getAsInt();
numbers.removeIf( i -> i == minValueFirst );
final int minValueSecond = numbers.stream().mapToInt( i -> i ).min().getAsInt();
numbers.removeIf( i -> i == minValueSecond );
final int sum = minValueFirst + minValueSecond;
numbers.addLast(sum);
System.out.println(" => " + minValueFirst + " + " + minValueSecond + " = " + sum);
}
System.out.println(numbers);
}
}
- Output:
[6, 81, 243, 14, 25, 49, 123, 69, 11] => 6 + 11 = 17 [81, 243, 14, 25, 49, 123, 69, 17] => 14 + 17 = 31 [81, 243, 25, 49, 123, 69, 31] => 25 + 31 = 56 [81, 243, 49, 123, 69, 56] => 49 + 56 = 105 [81, 243, 123, 69, 105] => 69 + 81 = 150 [243, 123, 105, 150] => 105 + 123 = 228 [243, 150, 228] => 150 + 228 = 378 [243, 378] => 243 + 378 = 621 [621]
Adapted from Wren
Works with gojq, the Go implementation of jq
With sorting
def task_with_sorting:
foreach range(1; length) as $i ( {a: .};
.a |= sort
| .emit = "Sorted list: \(.a)\n"
| (.a[0] + .a[1]) as $sum
| .emit += "Two smallest: \(.a[0]) + \(.a[1]) = \($sum)"
| .a += [$sum]
| .a |= .[2:] ;
.emit,
(select(.a|length==1) | "Last item is \(.a[0]).") );
[6, 81, 243, 14, 25, 49, 123, 69, 11]
| task_with_sorting- Output:
Sorted list: [6,11,14,25,49,69,81,123,243] Two smallest: 6 + 11 = 17 Sorted list: [14,17,25,49,69,81,123,243] Two smallest: 14 + 17 = 31 Sorted list: [25,31,49,69,81,123,243] Two smallest: 25 + 31 = 56 Sorted list: [49,56,69,81,123,243] Two smallest: 49 + 56 = 105 Sorted list: [69,81,105,123,243] Two smallest: 69 + 81 = 150 Sorted list: [105,123,150,243] Two smallest: 105 + 123 = 228 Sorted list: [150,228,243] Two smallest: 150 + 228 = 378 Sorted list: [243,378] Two smallest: 243 + 378 = 621 Last item is 621.
Without sorting
def min_index:
. as $in
| reduce range(0; length) as $i ( null;
$in[$i] as $x
| if . == null then {ix: 0, min: $x}
elif $x < .min then {ix: $i, min: $x}
else . end)
| .ix;
def task_without_sorting:
# Output: [min, remainder]
def remove_min:
min_index as $ix
| [.[$ix], (.[:$ix] + .[$ix + 1:])];
foreach range(1; length) as $i ( {a: .};
.emit = "Unsorted list: \(.a)\n"
| (.a | remove_min) as [$m1, $x]
| ($x | remove_min) as [$m2, $y]
| ($m1 + $m2) as $sum
| .emit += "Two smallest: \($m1) + \($m2) = \($sum)"
| .a = $y + [$sum] ;
.emit,
(select(.a|length==1) | "Last item is \(.a[0]).") );
[6, 81, 243, 14, 25, 49, 123, 69, 11]
| task_without_sorting- Output:
Unsorted list: [6,81,243,14,25,49,123,69,11] Two smallest: 6 + 11 = 17 Unsorted list: [81,243,14,25,49,123,69,17] Two smallest: 14 + 17 = 31 Unsorted list: [81,243,25,49,123,69,31] Two smallest: 25 + 31 = 56 Unsorted list: [81,243,49,123,69,56] Two smallest: 49 + 56 = 105 Unsorted list: [81,243,123,69,105] Two smallest: 69 + 81 = 150 Unsorted list: [243,123,105,150] Two smallest: 105 + 123 = 228 Unsorted list: [243,150,228] Two smallest: 150 + 228 = 378 Unsorted list: [243,378] Two smallest: 243 + 378 = 621 Last item is 621.
list = [6, 81, 243, 14, 25, 49, 123, 69, 11]
function addleastreduce!(lis)
while length(lis) > 1
push!(lis, popat!(lis, last(findmin(lis))) + popat!(lis, last(findmin(lis))))
println("Interim list: $lis")
end
return lis
end
@show list, addleastreduce!(copy(list))
- Output:
Interim list: [81, 243, 14, 25, 49, 123, 69, 17] Interim list: [81, 243, 25, 49, 123, 69, 31] Interim list: [81, 243, 49, 123, 69, 56] Interim list: [81, 243, 123, 69, 105] Interim list: [243, 123, 105, 150] Interim list: [243, 150, 228] Interim list: [243, 378] Interim list: [621] (list, addleastreduce!(copy(list))) = ([6, 81, 243, 14, 25, 49, 123, 69, 11], [621])
With and without sorting
list = {6, 81, 243, 14, 25, 49, 123, 69, 11};
Print[list]
Do[
poss = Ordering[list, 2];
extr = Extract[list, List /@ poss];
extr //= Total;
list = Delete[list, List /@ poss];
AppendTo[list, extr];
Print[list]
,
{Length[list] - 1}
]
- Output:
{6,81,243,14,25,49,123,69,11}
{81,243,14,25,49,123,69,17}
{81,243,25,49,123,69,31}
{81,243,49,123,69,56}
{81,243,123,69,105}
{243,123,105,150}
{243,150,228}
{243,378}
{621}
cascade(list) := while length(list) > 1 do (
m1: lmin(list), list: delete(m1, list, 1),
m2: lmin(list), list: delete(m2, list, 1),
list: endcons(m1+m2, list),
print(list)
)$
cascade([6, 81, 243, 14, 25, 49, 123, 69, 11]);
- Output:
[81,243,14,25,49,123,69,17] [81,243,25,49,123,69,31] [81,243,49,123,69,56] [81,243,123,69,105] [243,123,105,150] [243,150,228] [243,378] [621] done
With sorting
We sort in descending order as it is more efficient.
# With sorting.
import algorithm, strformat
proc extractAndAddTwoSmallest(list: var seq[int]) =
list.sort(Descending)
stdout.write &"Descending sorted list: {list}"
let min1 = list.pop()
let min2 = list.pop()
echo &"; two smallest: {min1} and {min2}; sum = {min1 + min2}"
list.add min1 + min2
var list = @[6, 81, 243, 14, 25, 49, 123, 69, 11]
while list.len >= 2:
list.extractAndAddTwoSmallest()
echo &"Last item is {list[0]}."
- Output:
Descending sorted list: @[243, 123, 81, 69, 49, 25, 14, 11, 6]; two smallest: 6 and 11; sum = 17 Descending sorted list: @[243, 123, 81, 69, 49, 25, 17, 14]; two smallest: 14 and 17; sum = 31 Descending sorted list: @[243, 123, 81, 69, 49, 31, 25]; two smallest: 25 and 31; sum = 56 Descending sorted list: @[243, 123, 81, 69, 56, 49]; two smallest: 49 and 56; sum = 105 Descending sorted list: @[243, 123, 105, 81, 69]; two smallest: 69 and 81; sum = 150 Descending sorted list: @[243, 150, 123, 105]; two smallest: 105 and 123; sum = 228 Descending sorted list: @[243, 228, 150]; two smallest: 150 and 228; sum = 378 Descending sorted list: @[378, 243]; two smallest: 243 and 378; sum = 621 Last item is 621.
Without sorting
We could use the function minIndex from module sequtils but it would be less efficient. We used a single loop instead. Please note that we remove the elements using function del which is O(1) rather than function delete which is O(n).
# Without sorting.
import strformat
proc extractAndAddTwoSmallest(list: var seq[int]) =
var min1, min2 = int.high
var imin1, imin2 = -1
for i, val in list:
if val < min1:
min2 = min1
min1 = val
imin2 = imin1
imin1 = i
elif val < min2:
min2 = val
imin2 = i
echo &"List: {list}; two smallest: {min1}@{imin1} and {min2}@{imin2}; sum = {min1 + min2}"
if imin1 > imin2: swap imin1, imin2 # Make sure "imin2" is the greatest index.
list.del imin2
list.del imin1
list.add min1 + min2
var list = @[6, 81, 243, 14, 25, 49, 123, 69, 11]
while list.len >= 2:
list.extractAndAddTwoSmallest()
echo &"Last item is {list[0]}."
- Output:
List: @[6, 81, 243, 14, 25, 49, 123, 69, 11]; two smallest: 6@0 and 11@8; sum = 17 List: @[69, 81, 243, 14, 25, 49, 123, 17]; two smallest: 14@3 and 17@7; sum = 31 List: @[69, 81, 243, 123, 25, 49, 31]; two smallest: 25@4 and 31@6; sum = 56 List: @[69, 81, 243, 123, 49, 56]; two smallest: 49@4 and 56@5; sum = 105 List: @[69, 81, 243, 123, 105]; two smallest: 69@0 and 81@1; sum = 150 List: @[123, 105, 243, 150]; two smallest: 105@1 and 123@0; sum = 228 List: @[243, 150, 228]; two smallest: 150@1 and 228@2; sum = 378 List: @[243, 378]; two smallest: 243@0 and 378@1; sum = 621 Last item is 621.
use strict;
use warnings;
use feature 'say';
use List::AllUtils <min firstidx>;
my @list = <6 81 243 14 25 49 123 69 11>;
say " Original @list";
push @list, get(min @list) + get(min @list) and say "@list" while @list > 1;
sub get {
my($min) = @_;
splice @list, (firstidx { $min == $_ } @list), 1;
printf " %3d ", $min;
$min;
}
- Output:
Original 6 81 243 14 25 49 123 69 11 6 11 81 243 14 25 49 123 69 17 14 17 81 243 25 49 123 69 31 25 31 81 243 49 123 69 56 49 56 81 243 123 69 105 69 81 243 123 105 150 105 123 243 150 228 150 228 243 378 243 378 621
More List::AllUtils fun
#!/usr/bin/perl
use strict; # https://rosettacode.org/wiki/Last_list_item
use warnings;
use List::AllUtils qw( sum min extract_first_by );
my @list = <6 81 243 14 25 49 123 69 11>;
print "@list\n";
push @list, sum
map { my $min = min @list; extract_first_by { $_ == $min } @list } 1, 2
and print "@list\n" while @list > 1;
- Output:
6 81 243 14 25 49 123 69 11 81 243 14 25 49 123 69 17 81 243 25 49 123 69 31 81 243 49 123 69 56 81 243 123 69 105 243 123 105 150 243 150 228 243 378 621
With sorting
with javascript_semantics sequence list = {6, 81, 243, 14, 25, 49, 123, 69, 11} while length(list)>1 do list = sort(deep_copy(list)) integer l1 = list[1], l2 = list[2], l12 = l1+l2 printf(1,"Sorted list: %V, two smallest: %d + %d = %d\n",{list,l1,l2,l12}) list[1..2] = {l12} end while printf(1,"Last item is %d\n",list)
- Output:
Sorted list: {6,11,14,25,49,69,81,123,243}, two smallest: 6 + 11 = 17
Sorted list: {14,17,25,49,69,81,123,243}, two smallest: 14 + 17 = 31
Sorted list: {25,31,49,69,81,123,243}, two smallest: 25 + 31 = 56
Sorted list: {49,56,69,81,123,243}, two smallest: 49 + 56 = 105
Sorted list: {69,81,105,123,243}, two smallest: 69 + 81 = 150
Sorted list: {105,123,150,243}, two smallest: 105 + 123 = 228
Sorted list: {150,228,243}, two smallest: 150 + 228 = 378
Sorted list: {243,378}, two smallest: 243 + 378 = 621
Last item is 621
Without sorting
with javascript_semantics sequence list = {6, 81, 243, 14, 25, 49, 123, 69, 11} while length(list)>1 do printf(1,"List: %V, two smallest: ",{list}) integer l1, l2 = 0 for i=1 to 2 do l1 = l2 integer ldx = smallest(list,true) l2 = list[ldx] list = list[1..ldx-1] & list[ldx+1..$] end for printf(1,"%d + %d = %d\n",{l1,l2,l1+l2}) list &= l1+l2 end while printf(1,"Last item is %d\n",list)
- Output:
List: {6,81,243,14,25,49,123,69,11}, two smallest: 6 + 11 = 17
List: {81,243,14,25,49,123,69,17}, two smallest: 14 + 17 = 31
List: {81,243,25,49,123,69,31}, two smallest: 25 + 31 = 56
List: {81,243,49,123,69,56}, two smallest: 49 + 56 = 105
List: {81,243,123,69,105}, two smallest: 69 + 81 = 150
List: {243,123,105,150}, two smallest: 105 + 123 = 228
List: {243,150,228}, two smallest: 150 + 228 = 378
List: {243,378}, two smallest: 243 + 378 = 621
Last item is 621
local a = {6, 81, 243, 14, 25, 49, 123, 69, 11}
repeat
a:sort()
print($"Sorted list: {a:concat(", ")}")
local sum = a[1] + a[2]
print($"Two smallest: {a[1]} + {a[2]} = {sum}")
a:insert(sum)
a:remove(1)
a:remove(1)
until #a == 1
print($"Last item is {a[1]}.")
- Output:
Sorted list: 6, 11, 14, 25, 49, 69, 81, 123, 243 Two smallest: 6 + 11 = 17 Sorted list: 14, 17, 25, 49, 69, 81, 123, 243 Two smallest: 14 + 17 = 31 Sorted list: 25, 31, 49, 69, 81, 123, 243 Two smallest: 25 + 31 = 56 Sorted list: 49, 56, 69, 81, 123, 243 Two smallest: 49 + 56 = 105 Sorted list: 69, 81, 105, 123, 243 Two smallest: 69 + 81 = 150 Sorted list: 105, 123, 150, 243 Two smallest: 105 + 123 = 228 Sorted list: 150, 228, 243 Two smallest: 150 + 228 = 378 Sorted list: 243, 378 Two smallest: 243 + 378 = 621 Last item is 621.
With sorted lists
%! last_list_item(+List, -Last) is det.
last_list_item(List, Last) :-
msort(List, Sorted),
ignore(( debugging(last_list_item), writeln('List' = Sorted) )),
last_list_item_(Sorted, Last).
last_list_item_([Last], Last) :- !.
last_list_item_([X, Y | List0], Last) :-
Z is X + Y,
msort([Z | List0], List),
ignore(( debugging(last_list_item), writeln('List' = List) )),
last_list_item_(List, Last).
- Output:
At the top-level, using library(debug) to toggle printing each step.
?- last_list_item([6, 81, 243, 14, 25, 49, 123, 69, 11], LastItem).
LastItem = 621.
?- debug(last_list_item).
true.
?- last_list_item([6, 81, 243, 14, 25, 49, 123, 69, 11], LastItem).
List=[6,11,14,25,49,69,81,123,243]
List=[14,17,25,49,69,81,123,243]
List=[25,31,49,69,81,123,243]
List=[49,56,69,81,123,243]
List=[69,81,105,123,243]
List=[105,123,150,243]
List=[150,228,243]
List=[243,378]
List=[621]
LastItem = 621.
With a heap
Use a heap instead of sorting the list each iteration.
:- use_module(library(heaps)).
last_list_item_heap(List, Last) :-
pairs_keys(Pairs, List),
list_to_heap(Pairs, Heap),
last_list_item_heap_(Heap, Last).
last_list_item_heap_(Heap0, Last) :-
get_from_heap(Heap0, Value0, _, Heap1),
( get_from_heap(Heap1, Value1, _, Heap2)
-> Value is Value0 + Value1,
ignore(( debugging(last_list_item_heap), writeln(Value is Value0 + Value1) )),
add_to_heap(Heap2, Value, _, Heap),
last_list_item_heap_(Heap, Last)
; Value0 = Last
).
- Output:
?- last_list_item_heap([6, 81, 243, 14, 25, 49, 123, 69, 11], LastItem).
LastItem = 621.
?- debug(last_list_item_heap), last_list_item_heap([6, 81, 243, 14, 25, 49, 123, 69, 11], LastItem).
17 is 6+11
31 is 14+17
56 is 25+31
105 is 49+56
150 is 69+81
228 is 105+123
378 is 150+228
621 is 243+378
LastItem = 621.
""" Rosetta code task: Last list item """
def add_least_reduce(lis):
""" Reduce lis: sum least two elements adding sum to list. Will take len(list) - 1 steps """
while len(lis) > 1:
lis.append(lis.pop(lis.index(min(lis))) + lis.pop(lis.index(min(lis))))
print('Interim list:', lis)
return lis
LIST = [6, 81, 243, 14, 25, 49, 123, 69, 11]
print(LIST, ' ==> ', add_least_reduce(LIST.copy()))
- Output:
Interim list: [81, 243, 14, 25, 49, 123, 69, 17] Interim list: [81, 243, 25, 49, 123, 69, 31] Interim list: [81, 243, 49, 123, 69, 56] Interim list: [81, 243, 123, 69, 105] Interim list: [243, 123, 105, 150] Interim list: [243, 150, 228] Interim list: [243, 378] Interim list: [621] [6, 81, 243, 14, 25, 49, 123, 69, 11] ==> [621]
[ behead
-1 swap rot witheach
[ 2dup > if
[ i^ swap
2swap drop ]
drop ]
drop 1+ ] is least ( [ --> n )
' [ 6 81 243 14 25 49 123 69 11 ]
[ dup echo cr
dup size 1 > while
dup least pluck
swap
dup least pluck
rot + join
again ]
0 peek echo- Output:
[ 6 81 243 14 25 49 123 69 11 ] [ 81 243 14 25 49 123 69 17 ] [ 81 243 25 49 123 69 31 ] [ 81 243 49 123 69 56 ] [ 81 243 123 69 105 ] [ 243 123 105 150 ] [ 243 150 228 ] [ 243 378 ] [ 621 ] 621
collapse <- function(v){
while(length(v)>1){
m1 <- min(v)
v <- v[-which.min(v)]
m2 <- min(v)
v <- v[-which.min(v)]
v <- c(v, m1+m2)
print(v)
}
}
collapse(c(6, 81, 243, 14, 25, 49, 123, 69, 11))
- Output:
[1] 81 243 14 25 49 123 69 17 [1] 81 243 25 49 123 69 31 [1] 81 243 49 123 69 56 [1] 81 243 123 69 105 [1] 243 123 105 150 [1] 243 150 228 [1] 243 378 [1] 621
Uses no sorting; does not modify overall list order while processing.
say ' Original ', my @list = 6, 81, 243, 14, 25, 49, 123, 69, 11;
say push @list: get(min @list) + get(min @list) while @list > 1;
sub get ($min) {
@list.splice: @list.first(* == $min, :k), 1;
printf " %3d ", $min;
$min;
}
- Output:
Original [6 81 243 14 25 49 123 69 11] 6 11 [81 243 14 25 49 123 69 17] 14 17 [81 243 25 49 123 69 31] 25 31 [81 243 49 123 69 56] 49 56 [81 243 123 69 105] 69 81 [243 123 105 150] 105 123 [243 150 228] 150 228 [243 378] 243 378 [621]
With sorting
/* REXX */
List = '6 81 243 14 25 49 123 69 11'
Do Until words(list)=1
list=wordsort(list)
Say 'Sorted list:' list
Parse Var list a b c
Say 'Two smallest:' a '+' b '=' (a+b)
list=(a+b) c
End
Say 'Last item:' list
Exit
wordsort: Procedure
/**********************************************************************
* Sort the list of words supplied as argument. Return the sorted list
**********************************************************************/
Parse Arg wl
wa.=''
wa.0=0
Do While wl<>''
Parse Var wl w wl
Do i=1 To wa.0
If wa.i>w Then Leave
End
If i<=wa.0 Then Do
Do j=wa.0 To i By -1
ii=j+1
wa.ii=wa.j
End
End
wa.i=w
wa.0=wa.0+1
End
swl=''
Do i=1 To wa.0
swl=swl wa.i
End
Return strip(swl)
- Output:
Sorted list: 6 11 14 25 49 69 81 123 243 Two smallest: 6 + 11 = 17 Sorted list: 14 17 25 49 69 81 123 243 Two smallest: 14 + 17 = 31 Sorted list: 25 31 49 69 81 123 243 Two smallest: 25 + 31 = 56 Sorted list: 49 56 69 81 123 243 Two smallest: 49 + 56 = 105 Sorted list: 69 81 105 123 243 Two smallest: 69 + 81 = 150 Sorted list: 105 123 150 243 Two smallest: 105 + 123 = 228 Sorted list: 150 228 243 Two smallest: 150 + 228 = 378 Sorted list: 243 378 Two smallest: 243 + 378 = 621 Last item: 621
Without sorting
/* REXX */
List = '6 81 243 14 25 49 123 69 11'
Do Until words(list)=1
Say 'List:' list
a=getmin()
b=getmin()
Say 'Two smallest:' a '+' b '=' (a+b)
list=list (a+b)
End
Say 'Last item:' list
Exit
getmin: Procedure Expose list
/* Return the smallest element of list and remove it from list */
min=1e9
Do i=1 To words(list)
If word(list,i)<min Then Do
m=word(list,i)
min=m
j=i
End
End
list=subword(list,1,j-1) subword(list,j+1)
Return m
- Output:
List: 6 81 243 14 25 49 123 69 11 Two smallest: 6 + 11 = 17 List: 81 243 14 25 49 123 69 17 Two smallest: 14 + 17 = 31 List: 81 243 25 49 123 69 31 Two smallest: 25 + 31 = 56 List: 81 243 49 123 69 56 Two smallest: 49 + 56 = 105 List: 81 243 123 69 105 Two smallest: 69 + 81 = 150 List: 243 123 105 150 Two smallest: 105 + 123 = 228 List: 243 150 228 Two smallest: 150 + 228 = 378 List: 243 378 Two smallest: 243 + 378 = 621 Last item: 621
With sorting
see "working..." + nl
List = [6,81,243,14,25,49,123,69,11]
n = 0
while true
n++
List = sort(List)
first = List[1]
second = List[2]
ind1 = find(List,first)
ind2 = find(List,second)
if ind1 < ind2
del(List,ind2)
del(List,ind1)
else
del(List,ind1)
del(List,ind2)
ok
sum = first + second
add(List,sum)
if len(List) = 1
exit
ok
if n = 1
see nl + "List = "
showArray(List)
see nl
ok
showList(first,second,sum,List)
end
see "Last item is: " +List[1] + nl
see "done..." + nl
func showList(first,second,sum,List)
see "two smallest is = " + first + " + " + second + " = " + sum + nl
see "List = "
showArray(List)
func showArray(array)
txt = ""
see "["
for n = 1 to len(array)
txt = txt + array[n] + ","
next
txt = left(txt,len(txt)-1)
txt = txt + "]"
see txt + nl- Output:
working... List = [14,25,49,69,81,123,243,17] two smallest is = 6 + 11 = 17 List = [14,25,49,69,81,123,243,17] two smallest is = 14 + 17 = 31 List = [25,49,69,81,123,243,31] two smallest is = 25 + 31 = 56 List = [49,69,81,123,243,56] two smallest is = 49 + 56 = 105 List = [69,81,123,243,105] two smallest is = 69 + 81 = 150 List = [105,123,243,150] two smallest is = 105 + 123 = 228 List = [150,243,228] two smallest is = 150 + 228 = 378 List = [243,378] Last item is: 621 done...
Without sorting
see "working..." + nl
List = [6,81,243,14,25,49,123,69,11]
n = 0
while true
n++
if n = 1
see nl + "List = "
showArray(List)
see nl
ok
first = min(List)
ind1 = find(List,first)
del(List,ind1)
second = min(List)
ind2 = find(List,second)
del(List,ind2)
sum = first + second
add(List,sum)
if len(List) = 1
exit
ok
showList(first,second,sum,List)
end
see "Last item is: " +List[1] + nl
see "done..." + nl
func showList(first,second,sum,List)
see "two smallest is = " + first + " + " + second + " = " + sum + nl
see "List = "
showArray(List)
func showArray(array)
txt = ""
see "["
for n = 1 to len(array)
txt = txt + array[n] + ","
next
txt = left(txt,len(txt)-1)
txt = txt + "]"
see txt + nl- Output:
working... List = [6,81,243,14,25,49,123,69,11] two smallest is = 6 + 11 = 17 List = [81,243,14,25,49,123,69,17] two smallest is = 14 + 17 = 31 List = [81,243,25,49,123,69,31] two smallest is = 25 + 31 = 56 List = [81,243,49,123,69,56] two smallest is = 49 + 56 = 105 List = [81,243,123,69,105] two smallest is = 69 + 81 = 150 List = [243,123,105,150] two smallest is = 105 + 123 = 228 List = [243,150,228] two smallest is = 150 + 228 = 378 List = [243,378] Last item is: 621 done...
« IF DUP SIZE 2 > THEN
DUP SORT 1 2 SUB → b
« DUP 1 « b SWAP POS NOT » DOLIST
SWAP IFT b
»
ELSE { } SWAP END
∑LIST +
IF DUP SIZE 1 > THEN DUP LASTL END
» 'LASTL' STO
- Output:
9: { 6 11 14 25 49 69 81 123 243 }
8: { 14 25 49 69 81 123 243 17 }
7: { 25 49 69 81 123 243 31 }
6: { 49 69 81 123 243 56 }
5: { 69 81 123 243 105 }
4: { 123 243 105 150 }
3: { 243 150 228 }
2: { 243 378 }
1: { 621 }
p original = [6, 81, 243, 14, 25, 49, 123, 69, 11]
until original.size == 1 do
mins = original.min(2)
mins.each{|el| original.delete_at(original.index(el)) }
p original << mins.sum
end
- Output:
[6, 81, 243, 14, 25, 49, 123, 69, 11] [81, 243, 14, 25, 49, 123, 69, 17] [81, 243, 25, 49, 123, 69, 31] [81, 243, 49, 123, 69, 56] [81, 243, 123, 69, 105] [243, 123, 105, 150] [243, 150, 228] [243, 378] [621]
With sorting
var k = 2
var list = [6, 81, 243, 14, 25, 49, 123, 69, 11]
while (list.len >= k) {
var a = list.sort!.shift(k)
list << a.sum
say "#{a.map{'%3s' % _}.join(' ')} : #{list}"
}
- Output:
6 11 : [14, 25, 49, 69, 81, 123, 243, 17] 14 17 : [25, 49, 69, 81, 123, 243, 31] 25 31 : [49, 69, 81, 123, 243, 56] 49 56 : [69, 81, 123, 243, 105] 69 81 : [105, 123, 243, 150] 105 123 : [150, 243, 228] 150 228 : [243, 378] 243 378 : [621]
Without sorting
var k = 2
var list = [6, 81, 243, 14, 25, 49, 123, 69, 11]
while (list.len >= k) {
var a = gather {
k.times {
take(var v = list.min)
list.delete_first(v)
}
}
list << a.sum
say "#{a.map{'%3s' % _}.join(' ')} : #{list}"
}
- Output:
6 11 : [81, 243, 14, 25, 49, 123, 69, 17] 14 17 : [81, 243, 25, 49, 123, 69, 31] 25 31 : [81, 243, 49, 123, 69, 56] 49 56 : [81, 243, 123, 69, 105] 69 81 : [243, 123, 105, 150] 105 123 : [243, 150, 228] 150 228 : [243, 378] 243 378 : [621]
With sorting
fn main() {
mut a := [6, 81, 243, 14, 25, 49, 123, 69, 11]
for a.len > 1 {
a.sort()
println("Sorted list: $a")
sum := a[0] + a[1]
println("Two smallest: ${a[0]} + ${a[1]} = $sum")
a << sum
a = a[2..].clone()
}
println("Last item is ${a[0]}.")
}
- Output:
Sorted list: [6, 11, 14, 25, 49, 69, 81, 123, 243] Two smallest: 6 + 11 = 17 Sorted list: [14, 17, 25, 49, 69, 81, 123, 243] Two smallest: 14 + 17 = 31 Sorted list: [25, 31, 49, 69, 81, 123, 243] Two smallest: 25 + 31 = 56 Sorted list: [49, 56, 69, 81 123, 243] Two smallest: 49 + 56 = 105 Sorted list: [69, 81, 105, 123, 243] Two smallest: 69 + 81 = 150 Sorted list: [105, 123, 150, 243] Two smallest: 105 + 123, = 228 Sorted list: [150, 228, 243] Two smallest: 150 + 228, = 378 Sorted list: [243, 378] Two smallest: 243 + 378 = 621 Last item is 621.
Without sorting
fn find_min(a []int) (int, int) {
mut ix := 0
mut min := a[0]
for i in 1..a.len {
if a[i] < min {
ix = i
min = a[i]
}
}
return min, ix
}
fn main() {
mut a := [6, 81, 243, 14, 25, 49, 123, 69, 11]
for a.len > 1 {
println("List: $a")
mut s := [2]int{}
for i in 0..2 {
min, ix := find_min(a)
s[i] = min
a.delete(ix)
}
sum := s[0] + s[1]
println("Two smallest: ${s[0]} + ${s[1]} = $sum")
a << sum
}
println("Last item is ${a[0]}.")
}
- Output:
List: [6, 81, 243, 14, 25, 49, 123, 69, 11] Two smallest: 6 + 11 = 17 List: [81, 243, 14, 25, 49, 123, 69, 17] Two smallest: 14 + 17 = 31 List: [81, 243, 25, 49, 123, 69, 31] Two smallest: 25 + 31 = 56 List: [81, 243, 49, 123, 69, 56] Two smallest: 49 + 56 = 105 List: [81, 243, 123, 69, 105] Two smallest: 69 + 81 = 150 List: [24,3 123, 105, 150] Two smallest: 105 + 123 = 228 List: [243, 150, 228] Two smallest: 150 + 228 = 378 List: [243, 378] Two smallest: 243 + 378 = 621 Last item is 621.
With sorting
var a = [6, 81, 243, 14, 25, 49, 123, 69, 11]
while (a.count > 1) {
a.sort()
System.print("Sorted list: %(a)")
var sum = a[0] + a[1]
System.print("Two smallest: %(a[0]) + %(a[1]) = %(sum)")
a.add(sum)
a = a[2..-1]
}
System.print("Last item is %(a[0]).")
- Output:
Sorted list: [6, 11, 14, 25, 49, 69, 81, 123, 243] Two smallest: 6 + 11 = 17 Sorted list: [14, 17, 25, 49, 69, 81, 123, 243] Two smallest: 14 + 17 = 31 Sorted list: [25, 31, 49, 69, 81, 123, 243] Two smallest: 25 + 31 = 56 Sorted list: [49, 56, 69, 81, 123, 243] Two smallest: 49 + 56 = 105 Sorted list: [69, 81, 105, 123, 243] Two smallest: 69 + 81 = 150 Sorted list: [105, 123, 150, 243] Two smallest: 105 + 123 = 228 Sorted list: [150, 228, 243] Two smallest: 150 + 228 = 378 Sorted list: [243, 378] Two smallest: 243 + 378 = 621 Last item is 621.
Without sorting
var findMin = Fn.new { |a|
var ix = 0
var min = a[0]
for (i in 1...a.count) {
if (a[i] < min) {
ix = i
min = a[i]
}
}
return [min, ix]
}
var a = [6, 81, 243, 14, 25, 49, 123, 69, 11]
while (a.count > 1) {
System.print("List: %(a)")
var s = List.filled(2, 0)
for (i in 0..1) {
var m = findMin.call(a)
s[i] = m[0]
a.removeAt(m[1])
}
var sum = s[0] + s[1]
System.print("Two smallest: %(s[0]) + %(s[1]) = %(sum)")
a.add(sum)
}
System.print("Last item is %(a[0]).")
- Output:
List: [6, 81, 243, 14, 25, 49, 123, 69, 11] Two smallest: 6 + 11 = 17 List: [81, 243, 14, 25, 49, 123, 69, 17] Two smallest: 14 + 17 = 31 List: [81, 243, 25, 49, 123, 69, 31] Two smallest: 25 + 31 = 56 List: [81, 243, 49, 123, 69, 56] Two smallest: 49 + 56 = 105 List: [81, 243, 123, 69, 105] Two smallest: 69 + 81 = 150 List: [243, 123, 105, 150] Two smallest: 105 + 123 = 228 List: [243, 150, 228] Two smallest: 150 + 228 = 378 List: [243, 378] Two smallest: 243 + 378 = 621 Last item is 621.
int List, End, Sum, Item, Smallest, I, SI;
[List:= [6, 81, 243, 14, 25, 49, 123, 69, 11];
End:= 8; \last index
loop [for I:= 0 to End do \show List
[IntOut(0, List(I)); ChOut(0, ^ )];
CrLf(0);
if End = 0 then quit; \done when only one element
Sum:= 0; \find two smallest items
for Item:= 1 to 2 do
[Smallest:= -1>>1;
for I:= 0 to End do
if List(I) < Smallest then
[Smallest:= List(I); SI:= I];
Sum:= Sum + Smallest; \add them
for I:= SI to End-1 do \remove them
List(I):= List(I+1);
End:= End-1;
];
End:= End+1; \insert Sum at End
List(End):= Sum;
];
]- Output:
6 81 243 14 25 49 123 69 11 81 243 14 25 49 123 69 17 81 243 25 49 123 69 31 81 243 49 123 69 56 81 243 123 69 105 243 123 105 150 243 150 228 243 378 621