import java.util.Random;

public class TestLoops {
    public static final int VECTOR_SIZE = 10000;
    public static final int TRIES = 10;
    public static final int N = 10000000;

    static int forwardLoop(int v[]) {
        int s = 0;
        for (int i = 0; i < v.length; i++)
            s += v[i];
        return s;
    }

    static int revLoop(int v[]) {
        int s = 0;
        for (int i = v.length - 1; i >= 0; i--)
            s += v[i];
        return s;
    }

    static int revLoop2(int v[]) {
        int s = 0;
        for (int i = v.length; --i >= 0; )
            s += v[i];
        return s;
    }

    public static void main(String[] args) {
        long t1, t2;
        Random r = new Random(42);
        int[] v = new int[VECTOR_SIZE];
        for (int i = 0; i < v.length; i++)
            v[i] = r.nextInt(1000);

        int goodSum = forwardLoop(v);

        for (int test = 0; test < TRIES; test++) {
            t1 = System.currentTimeMillis();
            for (int j = 0; j < N; j++) {
                if (forwardLoop(v) != goodSum)
                    throw new RuntimeException();
            }
            t2 = System.currentTimeMillis();
            System.out.println("d1 = " + (t2 - t1));

            t1 = System.currentTimeMillis();
            for (int j = 0; j < N; j++) {
                if (revLoop(v) != goodSum)
                    throw new RuntimeException();
            }
            t2 = System.currentTimeMillis();
            System.out.println("d2 = " + (t2 - t1));

            t1 = System.currentTimeMillis();
            for (int j = 0; j < N; j++) {
                if (revLoop2(v) != goodSum)
                    throw new RuntimeException();
            }
            t2 = System.currentTimeMillis();
            System.out.println("d3 = " + (t2 - t1));
        }
    }
}