COS126

• Download InsertionTest.java

/*************************************************************************
 * Name:
 * Login:
 * Precept:
 *
 * Description: The method timeTrials() runs InsertionSort.sort() for
 * arrays of random double values. The first argument to the method is
 * the number of trials; the second argument is the length of the array.
 * Multiple trials produce more accurate results because insertion sort's
 * running time depends on the input and various system effects.
 *
 * Dependencies: StdOut.java
 *
 * Examples:
 * % java InsertionTest 10  
 *  1024 1.89 
 *  2048 5.00 
 *  4096 3.58 
 *  8192 4.09 
 * 16384 4.83 
 * 32768 3.96
 *************************************************************************/

public class InsertionTest {

    // runs InsertionSort.sort() for arrays of random double values
    public static double timeTrials(int M, int N) {
        Double[] a = new Double[N];
        double total = 0;
        for (int k = 0; k < M; k++) { 
            for (int i = 0; i < N; i++)
                a[i] = Math.random();
            Stopwatch s = new Stopwatch();
            Insertion.sort(a);
            total += s.elapsedTime();
        }
        return total;
    }

    public static void main(String[] args) {
        int M = Integer.parseInt(args[0]);
        double prev = timeTrials(M, 512);
        for (int N = 1024; true; N += N) {
            double curr =  timeTrials(M, N);
            StdOut.printf("%7d %4.2f\n", N, curr / prev);
            prev = curr;
        }
    }
}