if (compareElements(i, minIndex) < 0) {
          minIndex = i;
        }
      }
      return minIndex;
    }

    /** Returns the minimum child or {@code -1} if no child exists. */
    int findMinChild(int index) {
      return findMin(getLeftChildIndex(index), 2);
    }

    /** Returns the minimum grand child or -1 if no grand child exists. */
    int findMinGrandChild(int index) {