CSC300: Loop invariant [12/21] Previous pageContentsNext page

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package algs11;
import stdlib.*;
public class PlaygroundMax {
  public static double max (double[] a) {
    double m = a[0];
    for (int i = 1; i < a.length; i++) {
      /* m == max(a[0]...a[i-1]) */
      if (m < a[i]) { m = a[i]; }
    }
    /* m == max(a[0]...a[a.length-1]) */
    return m; 
  }
  public static void testMax (double expected, double[] a) {
    double actual = max (a);
    if (expected != actual) {
      StdOut.format ("max failed: Expecting [%d] Actual [%d] with argument %s\n", expected, actual, java.util.Arrays.toString(a));
    }
  }
  public static void main (String[] args) { 
    testMax(31, new double[] { 11, 21, 31 });
    testMax(31, new double[] { 11, 31, 21 });
    testMax(31, new double[] { 31, 11, 21 });
    testMax(21, new double[] { 21, 11 });
    testMax(21, new double[] { 11, 21 });
    testMax(11, new double[] { 11 });
    StdOut.println ("Finished tests");
  }
}

A loop invariant is something that is true every time, before executing the body of the loop

What about the empty array?

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