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package com.oracle.graal.python.benchmarks.interop;

import org.graalvm.polyglot.Value;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.infra.Blackhole;

public class PyEuler31 extends BenchRunner {

    @Param({"100"}) public int arg1;

    private Value newpat;
    private Value EMPTY;
    private Value COINS;

    @Setup
    public void setup() {
        System.out.println("### setup ...");
        this.newpat = this.context.eval("python", //
                        "def newpat(t, end, p):" + //
                                        "  return t[:end] + (p,)\n" + //
                                        "newpat");
        this.COINS = this.context.eval("python", "[1, 2, 5, 10, 20, 50, 100, 200]");
        this.EMPTY = this.context.eval("python", "()");
    }

    @Benchmark
    public void euler31(Blackhole bh) {
        int result = gen(EMPTY, 0, arg1);
        bh.consume(result);
        System.out.println("total number of different ways: " + result);
    }

    private int gen(Value pattern, int coinnum, int num) {
        int count = 0;
        int coin = geti(COINS, coinnum);
        for (int p = 0; p < (num / coin + 1); p++) {
            Value newpattern = newpat(pattern, coinnum, p);
            int bal = balance(newpattern);
            if (bal > num) {
                return count;
            } else if (bal == num) {
                count++;
            } else if (coinnum < (COINS.getArraySize() - 1)) {
                count += gen(newpattern, coinnum + 1, num);
            }
        }
        return count;
    }

    private int balance(Value pattern) {
        long size = pattern.getArraySize();
        int sum = 0;
        for (int i = 0; i < size; i++) {
            sum += geti(COINS, i) * geti(pattern, i);
        }
        return sum;
    }

    private Value newpat(Value t, int end, int p) {
        return this.newpat.execute(t, this.context.asValue(end), this.context.asValue(p));
    }
}
