Data Structures and Algorithm Analysis - Computer Science at ...

174 Chap. 5 Binary Trees/** Heapify contents of Heap */public void buildheap(){ for (int i=n/2-1; i>=0; i--) siftdown(i); }/** Put element in its correct place */private void siftdown(int pos) {assert (pos >= 0) && (pos < n) : "Illegal heap position";while (!isLeaf(pos)) {int j = leftchild(pos);if ((j= 0) return;DSutil.swap(Heap, pos, j);pos = j; // Move down}}/** Remove and return maximum value */public E removemax() {assert n > 0 : "Removing from empty heap";DSutil.swap(Heap, 0, --n); // Swap maximum with last valueif (n != 0) // Not on last elementsiftdown(0); // Put new heap root val in correct placereturn Heap[n];}/** Remove and return element at specified position */public E remove(int pos) {assert (pos >= 0) && (pos < n) : "Illegal heap position";if (pos == (n-1)) n--; // Last element, no work to be doneelse{DSutil.swap(Heap, pos, --n); // Swap with last value// If we just swapped in a big value, push it upwhile ((pos > 0) &&(Heap[pos].compareTo(Heap[parent(pos)]) > 0)) {DSutil.swap(Heap, pos, parent(pos));pos = parent(pos);}if (n != 0) siftdown(pos); // If it is little, push down}return Heap[n];}}Figure 5.19 (continued)