堆分爲大根堆(最大堆)和小根堆(最小堆),堆排序就是二叉堆的升級版,其實是一棵徹底二叉樹ios
不一樣的是這棵二叉樹裏每一個節點保證父節點都小於孩子節點ui
最後進行堆排序,將堆頂最小的節點(第一個)與最後一個節點(最大的節點)進行交換,對剩下的進行調節,令其知足最小堆spa
#include <iostream> #include <cstdlib> using namespace std; void MaxHeapIfy(int A[], int length, int i) //維護 { int left = i * 2; //節點i的左孩子 int right = i * 2 + 1; //節點i的右孩子節點 int largest = i; //默認父節點 if (left <= length && A[largest] < A[left]) //左孩子比父節點大 { largest = left; } if (right <= length && A[largest] < A[right]) //右孩子最大 { largest = right; } if (i != largest) //最大值不是父節點 { int temp = A[largest]; //exchange A[largest] = A[i]; A[i] = temp; MaxHeapIfy(A, length, largest); //繼續維護 } } void BuildMaxHeap(int A[], int length) //建堆 { for (int i = length / 2; i >= 1; i--) { MaxHeapIfy(A, length, i); } } void HeapSort(int A[], int length) //堆排 { int temp; BuildMaxHeap(A, length); //建堆 /* cout<<"建堆狀況:"; // for(int i = 1; i <= length; i++) cout<<A[i]<<" "; cout<<endl; */ for(int i = length; i >= 2;) { temp = A[i]; //交換堆的第一個元素和堆的最後一個元素 A[i] = A[1]; A[1] = temp; i--; //堆的大小減一 MaxHeapIfy(A, i, 1); //調堆 } } int main() { int A[] = {0, 4, 1, 23, 3, 2, 16, 9, 10, 14, 8, 7}; //0只作填充,填充A[0] /*int* A = new int[1001]; A[0] = 0; for(int i = 1; i <= 1000; i++) A[i] = rand()%10000 + 1;*/ int length = sizeof(A) / sizeof(int); // //int length = 1001; HeapSort(A, length - 1); for(int i = 1; i < length; i++) //cout cout<<A[i]<<" "; cout<<endl; return 0; }
原文爲https://blog.csdn.net/xjm199/article/details/18011321.net