#ifndef BINOMIAL_HEAP #define BINOMIAL_HEAP #include <vector> #include <algorithm> #include <iostream> template<typename T> struct BinomialNode { T val; BinomialNode *leftChild; BinomialNode *nextSibling; BinomialNode(const T &data, BinomialNode *left, BinomialNode *next) : val{ data }, leftChild{ left }, nextSibling{ next }{} BinomialNode(T &&data, BinomialNode *left, BinomialNode *next) : val{ std::move(data) }, leftChild{ left }, nextSibling{ next }{} }; template<typename K, typename Cmp = std::less<K>> class BinomialHeap { using BinomialNode = BinomialNode<K>; public: BinomialHeap() : curSize{ 0 }, trees(DEFAULT_TREES), cmp{}{ for (auto &root : trees) root = nullptr; } explicit BinomialHeap(const K &x) : curSize{ 1 }, trees(1), cmp{}{ trees[0] = new BinomialNode{ x, nullptr, nullptr }; } BinomialHeap(const BinomialHeap &rhs) : trees(rhs.trees.size()), curSize{ rhs.curSize } { for (std::size_t i = 0; i < rhs.trees.size(); ++i) { trees[i] = clone(rhs.trees[i]); } } BinomialHeap(BinomialHeap &&rhs) : trees{ std::move(rhs.trees) }, curSize{ rhs.curSize }{} BinomialHeap(const std::initializer_list<K> &ls) { BinomialHeap(); for (const auto &i : ls) push(i); } ~BinomialHeap() { clear(); } BinomialHeap &operator =(const BinomialHeap &rhs) { BinomialHeap copy{ rhs }; std::swap(*this, copy); return *this; } BinomialHeap &operator =(BinomialHeap &&rhs) { std::swap(curSize, rhs.curSize); std::swap(trees, rhs.trees); return *this; } // 清空堆 void clear() { for (auto &root : trees) clear(root); curSize = 0; } //是否为空 bool empty() const { return curSize == 0; } // 获取堆顶元素 const K &top() const { return trees[findMinIndex()]->val; // assert(curSize == 0) } //获取元素个数 std::size_t size() const { return curSize; } //合并堆 void merge(BinomialHeap &rhs) { if (this == &rhs) // 避免重名 return; curSize += rhs.curSize; if (curSize > capacity()) { // 扩容 auto oldNumTrees = trees.size(); auto newNumTrees = std::max(trees.size(), rhs.trees.size()) + 1; trees.resize(newNumTrees); for (std::size_t i = oldNumTrees; i < newNumTrees; ++i) trees[i] = nullptr; //对新的部分进行初始化 } BinomialNode *carry = nullptr; // 上一次合并过来的树, 一开始为空 //逐一合并, 类比二进制加法, 逐位相加 for (std::size_t i = 0, j = 1; j <= curSize; ++i, j <<= 1) { // 获得两棵树对应位置的结点 // t1->thisNode t2->rhsNode BinomialNode *t1 = trees[i]; BinomialNode *t2 = i < rhs.trees.size() ? rhs.trees[i] : nullptr; // 二进制 000-111 第一位是carry, 然后是t2 ,最后是t1 char whichCase = t1 == nullptr ? 0 : 1; whichCase += t2 == nullptr ? 0 : 2; whichCase += carry == nullptr ? 0 : 4; switch (whichCase) { // 000 and 001 case 0: /*non trees*/ case 1: /*only this*/ break; // 010 case 2: /*only rhs*/ trees[i] = t2; rhs.trees[i] = nullptr; break; case 3: // 011 this and rhs but no carry carry = combineTrees(t1, t2); trees[i] = rhs.trees[i] = nullptr; break; case 4: // 100 only carry trees[i] = carry; carry = nullptr; break; case 5: // 101 carry and this carry = combineTrees(carry, t1); trees[i] = nullptr; break; case 6: // 110 carry and rhs carry = combineTrees(carry, t2); rhs.trees[i] = nullptr; break; case 7: // 111 carry and rhs and this --> all trees[i] = carry; carry = combineTrees(t1, t2); rhs.trees[i] = nullptr; break; default: break; } } // 不用的东西归0 for (auto &root : rhs.trees) root = nullptr; rhs.curSize = 0; } //插入元素 void push(const K &x) { BinomialHeap oneIten(x); merge(oneIten); } void push(K &&x) { BinomialHeap oneItem(std::move(x)); merge(oneItem); } //删除堆顶元素 void pop() { auto minIndex = findMinIndex(); BinomialNode *oldRoot = trees[minIndex]; BinomialNode *deletedTree = oldRoot->leftChild; delete oldRoot; //构建新的堆 BinomialHeap deletedHeap; deletedHeap.trees.resize(minIndex + 1); deletedHeap.curSize = (1 << minIndex) - 1; for (int j = minIndex - 1; j >= 0; --j) { deletedHeap.trees[j] = deletedTree; deletedTree = deletedTree->nextSibling; deletedHeap.trees[j]->nextSibling = nullptr; } //新的堆合并过来 trees[minIndex] = nullptr; curSize -= deletedHeap.curSize + 1; merge(deletedHeap); } //auto show() const { return trees.size(); } private: const static int DEFAULT_TREES = 1; std::vector<BinomialNode *> trees; std::size_t curSize; Cmp cmp; std::size_t capacity() const { return (1 << (trees.size())) - 1; } void clear(BinomialNode *&r) { if (r != nullptr) { clear(r->leftChild); clear(r->nextSibling); delete r; r = nullptr; } } BinomialNode *clone(BinomialNode *r) const { if (r == nullptr) return nullptr; return new BinomialNode{ r->val, clone(r->leftChild), clone(r->nextSibling) }; } // 找到最小值对应的rank std::size_t findMinIndex() const { std::size_t i, index; for (i = 0; trees[i] == nullptr; ++i); // 顺序遍历获取最小值 for (index = i; i < trees.size(); ++i) if (trees[i] != nullptr && cmp(trees[i]->val, trees[index]->val)) index = i; return index; } //合并同样大小的两棵树 BinomialNode *combineTrees(BinomialNode *t1, BinomialNode *t2) { if (cmp(t2->val, t1->val)) return combineTrees(t2, t1); //让小的在前面 t2->nextSibling = t1->leftChild; t1->leftChild = t2; return t1; } }; #endif // !BINOMIAL_HEAP
来源:https://www.cnblogs.com/MasterYan576356467/p/12229292.html