數據結構複習之堆

馬上要找工作了，因此最近開始複習一下數據結構，早上撲騰了半天，把堆寫了一遍，不過太久沒寫了，實現的最簡單的思想，還是費了老半天調試了多次才寫完，也太水了……

#ifndef VLIB_VHEAP_H #define VLIB_VHEAP_H #include "algorithm_global.h" #include <vector> #include <cassert> _VLIB_BEGIN_ template <typename VT> class VHeap { //小頂堆 public: virtual ~VHeap() { } size_t size() const { return elems.size(); } bool empty() const { return elems.empty(); } void setValue(std::vector <VT> &values) { elems = values; if (values.empty()) return; for (int ix = (values.size() - 1) >> 1; ix >= 0; --ix) { heapDown(ix); } } void insert(const VT &data) { elems.push_back(data); heapUp(elems.size() - 1); } VT& top() { assert (!elems.empty()); return elems[0]; } void pop() { assert (!elems.empty()); elems[0] = elems.back(); elems.pop_back(); if (!elems.empty()) heapDown(0); } private: void heapUp(int n) { VT key = elems[n]; int cur = n; //parent of elems[n] int p = -1; for (; cur > 0; cur = p) { p = ((cur - 1) >> 1); if (key < elems[p]) { elems[cur] = elems[p]; } else break; } elems[cur] = key; } //將以n爲根的子樹建立成堆 void heapDown(int p) { int q = (p << 1) + 1; VT key = elems[p]; while (q < elems.size()) { if (q + 1< elems.size() && elems[q + 1] < elems[q]) ++q; if (elems[q] < key) elems[p] = elems[q]; else break; p = q; q = (p << 1) + 1; } assert (p < elems.size()); elems[p] = key; // } std::vector <VT> elems; }; _VLIB_END #endif