数据结构——最小堆

优先队列懒得打了

#include <iostream>
//#include<priority_queue>
using namespace std; 
const int DefaultSize=10;

template<class T>
class MinHeap {
public:
	MinHeap(int sz = DefaultSize);	//构造函数：建立空堆
	MinHeap(T arr[], int n);		//构造函数：通过一个数组创建堆
	~MinHeap() { delete[] heap; }	//析构函数
	bool insert(const T& x);		//将x插入到最小堆中
	bool removeMin(T& x);			//删除堆顶元素(min value)
	bool isTmpty() const;			//判断堆是否是空
	bool isFull() const;			//判断堆是否已满
	void makeTmpty();				//置空堆 
	void output();					//数组元素输出
private:
	T* heap;						//存放最小堆元素的数组
	int currentSize;				//最小堆中当前元素的个数
	int maxHeapSize;				//最小堆最多存放元素个数
	void siftDown(int start, int m);//从start到m下滑调整为最小堆
	void siftUp(int start);			//从start到0上滑调整为最小堆
};


template<class T>
MinHeap<T>::MinHeap(int sz) {
	maxHeapSize = (DefaultSize < sz) ? sz : DefaultSize;
	heap = new T[maxHeapSize];
	if (heap == NULL) {
		cerr << "内存分配失败" << endl;
		exit(1);
	}
	currentSize = 0;
}

template<class T>
MinHeap<T>::MinHeap(T arr[], int n) {
	maxHeapSize = (DefaultSize < n) ? n : DefaultSize;
	heap = new T[maxHeapSize];
	if (heap == NULL) {
		cerr << "内存分配失败" << endl;
		exit(1);
	}
	for (int i = 0; i < n; i++) {
		heap[i] = arr[i];							
	}
	currentSize = n;
	//利用完全二叉树中元素的排列规律，找到最初调整位置，也就是最后的分支节点
	int currentPos = (currentSize - 1) / 2;
	while (currentPos >= 0) {						
		siftDown(currentPos, currentSize - 1);		
		currentPos--;								
	}
}

template<class T>
void MinHeap<T>::output() {
	for (int i = 0; i < currentSize; i++) {
		cout << heap[i] << ' ';
	}
}

template<class T>
bool MinHeap<T>::isTmpty() const {
	return (0 == currentSize) ? true : false;
}

template<class T>
bool MinHeap<T>::isFull() const {
	return (maxHeapSize == currentSize) ? true : false;
}

template<class T>
void MinHeap<T>::makeTmpty() {
	currentSize = 0;
}

template<class T>
bool MinHeap<T>::insert(const T& x) {
	if (isFull()) {									//判断堆是否已经满
		cerr << "Heap Fulled" <<  endl;
		return false;								
	}
	heap[currentSize] = x;							//将x元素插入到数组最后
	siftUp(currentSize);
	currentSize++;									//对当前大小增加1
	return true;
}

template<class T>
bool MinHeap<T>::removeMin(T& x) {
	if (0 == currentSize) {
		cout << "Heap Tmptyed" << endl;
		return false;
	}
	x = heap[0];
	heap[0] = heap[currentSize - 1];
	currentSize--;
	siftDown(0, currentSize - 1);					//借助函数对堆再一次调整
	return true;
}

template<class T>
void MinHeap<T>::siftDown(int start, int m) {
	int i = start;
	int j = 2 * i + 1;								//通过公式2x+1求得x左子女位置
	T temp = heap[i];								//temp记录原来的的数据
	while (j <= m) {
		if (j < m && heap[j] > heap[j + 1]) {
			j = j + 1;								//j指向左右子女中较小的一个
		}
		if (heap[j] >= temp) {
			break;									
		}
		else {									
			heap[i] = heap[j];
			i = j;
			j = 2 * i + 1;
		}
	}
	heap[i] = temp;									
}

template<class T>
void MinHeap<T>::siftUp(int start) {
	int j = start;
	int i = (j - 1) / 2;
	T temp = heap[j];
	while (j > 0) {
		if (heap[i] <= temp) {
			break;
		}
		else {
			heap[j] = heap[i];
			j = i;
			i = (j - 1) / 2;
		}
	}
	heap[j] = temp;
}

int main()
{
	
	return 0;
}

标签：int,void,最小,start,heap,MinHeap,数据结构,currentSize
来源： https://blog.csdn.net/github_50047554/article/details/113802209