TheAlgorithms · badallogical · Jun 5, 2020
diff --git a/Others/RR_Scheduling.java b/Others/RR_Scheduling.java
@@ -0,0 +1,174 @@
+package Others;
+
+import java.io.BufferedReader;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+import java.io.InputStreamReader;
+import java.io.IOException;
+
+/**
+ * RR scheduling implememtation with the process queue as a list
+ *
+ * @author Badal
+ * @data 2 june 2020
+ */
+
+
+
+public class RR_Scheduling {
+
+	/**
+	 * Calculate the TurnAroundTime i.e burst_time + waiting time
+	 * 
+	 * @param n , number of processes
+	 * @param wTime , Waiting time of process
+	 * @param bTime , Burst time of processes
+	 * @param arrivalTime
+	 * @param tat, TurnAround Time of processes , to be calculated.
+	 */
+
+	 private static void findTurnAroundTime(int n, int[] wTime, int[] bTime, int[] arrivalTime, int[] tat){
+		// for all processes
+		for( int i = 0; i < n; i++ ){	
+			tat[i] = bTime[i] + wTime[i];	// it is equalent to completiontime - arrivaltime
+		}
+	}
+
+	/**
+	 * It find the wainting of the processes envolve in the execution
+	 * 
+	 * @param n
+	 * @param bTime
+	 * @param arrivalTime
+	 * @param quantum
+	 * @param wTime
+	 */
+	private static void findWaitingTime(int n, int[] bTime, int[] arrivalTime ,int quantum, int[] wTime){
+		// array to store remaing time of respective process
+		int[] rem_bt = new int[n];
+
+		int cpu_time = 0;
+
+		// initially it will be equal to the burst time of all processes respectively
+		for( int i = 0; i < n; i++ ) rem_bt[i] = bTime[i];
+
+
+
+		// get the processes queue
+		List<Integer> pQueue = new ArrayList<Integer>();
+
+		// get the processes by thier arrival time
+		while( pQueue.isEmpty() ){
+			for( int i = 0; i < n; i++){
+				if( arrivalTime[i] == cpu_time){
+					pQueue.add(i);
+				}
+			}
+
+			if( pQueue.isEmpty()){
+				cpu_time++;
+			}
+		}
+
+
+
+		// executed process
+		int	executedProcess = 0;
+		while(executedProcess != n){
+
+			// process all pQueue processes
+			for( int p = 0; p < pQueue.size(); p++){
+
+				// if not done 
+				if( rem_bt[ pQueue.get(p) ] > 0 ){
+
+					// partail execution
+					if( rem_bt[pQueue.get(p)] > quantum){
+
+						// collect all the processes that arrive under the execution 
+						for( int i = 0; i < n; i++){
+							if(  arrivalTime[i] > cpu_time && arrivalTime[i] < cpu_time + quantum ){
+								// add to pQueue
+								pQueue.add(i);
+							}
+						}
+
+						// update cpu_time
+						cpu_time += quantum;
+
+						// update rem_bt time
+						rem_bt[pQueue.get(p)] -= quantum;
+					}
+					else{
+
+
+
+						// collect all the processes that arrive under the execution 
+						for( int i = 0; i < n; i++){
+							if(  arrivalTime[i] > cpu_time && arrivalTime[i] < cpu_time + rem_bt[pQueue.get(p)]){
+								// add to pQueue
+								pQueue.add(i);
+							}
+						}
+
+						// udpate cpu_time
+						cpu_time += rem_bt[pQueue.get(p)];
+
+						// completely executed
+						rem_bt[pQueue.get(p)] = 0;
+
+						// fetch completion time and waiting time
+						int TurnAroundTime = cpu_time - arrivalTime[pQueue.get(p)];
+						wTime[pQueue.get(p)] = TurnAroundTime - bTime[pQueue.get(p)];
+
+						//update execute process
+						executedProcess++;
+
+					}
+				}
+
+
+
+				// get the processes by thier arrival time
+				for( int i = 0; i < n; i++ ){
+					if( arrivalTime[i] == cpu_time){
+						pQueue.add(i);
+					}
+				}
+			}
+
+		}
+	}
+
+
+	// take number of processes via command line
+	public static void main(String[] args) throws IOException{
+		BufferedReader br = new BufferedReader( new InputStreamReader( System.in ));
+
+		int processes = Integer.parseInt(br.readLine());
+		int[] arrivalTime = new int[processes];
+		int[] burstTime = new int[processes];
+		for( int i = 0; i < processes; i++ ){
+			arrivalTime[i] = Integer.parseInt(br.readLine());
+			burstTime[i] = Integer.parseInt(br.readLine());
+		}
+
+		int[] waitingTime = new int[processes];
+		int quantum = Integer.parseInt(br.readLine());
+
+		// find and print the waiting time of process after the RR scheduling 
+		findWaitingTime(processes, burstTime, arrivalTime, quantum, waitingTime);
+		for( int i = 0; i < processes; i++){
+			System.out.printf("Waiting time : P(%d) : %d\n" , i, waitingTime[i]);
+		}
+
+		// print th turnAroundTime of the process,
+		int[] tat = new int[processes];
+		findTurnAroundTime(processes, waitingTime, burstTime, arrivalTime, tat);
+		for( int i = 0; i < processes; i++ ){
+			System.out.printf("Turn Around Time : P(%d) : %d\n", i, tat[i]);
+		}
+	}
+
+}