HeapSort_t.Java

import java.util.Arrays;
import java.util.Collections;
class HeapSort {
  public static void main(String[] args) {
    var n = 7;
    var a = new Integer[7];
    for (var i = 0; i < n; i++) {
      a[i] = i;
    }  
    Collections.shuffle(Arrays.asList(a));

    for (var i : a) {
      System.out.printf("%3d", i);
    }
    System.out.println();

    for (var i = n - 1; i >= 0; i--) {
      for (var j = (i + 1) / 2 - 1; j >= 0; j--) {
        var c = j;
        var l = j * 2 + 1;
        if (a[c] < a[l]) c = l;
        var r = j * 2 + 2;
        if (r <= i && a[c] < a[r]) c = r;
        var t = a[c];
        a[c] = a[j];
        a[j] = t;
      }
      var t = a[0];
      a[0] = a[i];
      a[i] = t;
    }

    for (var i : a) {
      System.out.printf("%3d", i);
    }
    System.out.println();
  }
}