归并排序

时间复杂度O(N*logN)

空间复杂度O(N)

 

对应申请的临时存储空间，应该及时释放，避免内存猛增与内存泄露

 

#include<stdio.h>#include<stdlib.h>//array[begin...mid] is sorted//array[mid+1...end] is also sortedvoid merge(int *arr, int begin, int mid, int end){int leftLen = mid-begin+1;int rightLen = end-mid;int *left = new int[leftLen];int *right = new int[rightLen];for(int i=begin; i<=mid; i++){left[i-begin] = arr[i];}for(int i=mid+1; i<=end; i++){right[i-mid-1] = arr[i];}int i,j;int index = begin;for(i=j=0; i<leftLen && j<rightLen; ){if(left[i] < right[j]){arr[index++] = left[i++];}else{arr[index++] = right[j++];}}while(i<leftLen){arr[index++] = left[i++];}while(j<rightLen){arr[index++] = right[j++];}delete left;delete right;}void mergeSort(int *arr, int begin, int end){if(begin >= end)return ;int mid = (begin+end)/2;mergeSort(arr, begin, mid);mergeSort(arr, mid+1, end);merge(arr, begin, mid, end);}int main(){int arr[] = {4,2,8,1,5,3,9,7,6};mergeSort(arr, 0, 8);for(int i=0; i<9; i++){printf("%d ", arr[i]);}system("pause");return 0;}