0001 template <typename T> void Vector<T>::heapSort( Rank lo, Rank hi ) { // 0 <= lo < hi <= size
0002    T* A = _elem + lo; Rank n = hi - lo; heapify( A, n ); //将待排序区间建成一个完全二叉堆，O(n)
0003    while ( 0 < --n ) //反复地摘除最大元并归入已排序的后缀，直至堆空
0004       { swap( A[0], A[n] ); percolateDown( A, n, 0 ); } //堆顶与末元素对换，再下滤
0005 }