算法导论P17 归并排序

#include <stdio.h>#include <stdlib.h>#include <time.h>#include <iostream>#include <vector>// 输出数组元素void printArr(int* arr, int len){for (int i = 0; i < len; i++){printf("%d ", *(arr+i));}}// 随机生成数组数据void randArr(int* arr, int len, int maxVal){srand((int)time(0));for (int i = 0; i < len; i++){*(arr+i) = rand() % maxVal;}}// 合并子数组 arr[low...mid] 和子数组 arr[mid+1...high]void Merge(int* arr, int low, int mid, int high) // 如何归并是关键{//extern void *memcpy(void *dest, void *src, unsigned int count);int index;int* temp = new int[high-low+1]; // 临时空间用来存放合并后的数组int firstStart = low;int firstEnd = mid;int secondStart = mid+1;int secondEnd = high;for (index = 0; firstStart <= firstEnd && secondStart <= secondEnd; index++){if (arr[firstStart] <= arr[secondStart]){temp[index] = arr[firstStart];++firstStart;}else{temp[index] = arr[secondStart];++secondStart;}}// 第一个序列有剩余，直接拷贝粘贴if (firstStart <= firstEnd){memcpy(temp+index, arr+firstStart, (firstEnd-firstStart+1)*sizeof(int));}if (secondStart <= secondEnd){memcpy(temp+index, arr+secondStart, (secondEnd-secondStart+1)*sizeof(int));}// 将排序好的序列拷贝回数组memcpy(arr+low, temp, (high-low+1)*sizeof(int));// 释放内存空间delete temp;}void MergeSort(int* arr, int first, int last) // 分治递归思想{int mid = 0;if (first < last){mid = first + (last - first) / 2;// 分治思想，把数组平均分成两份// 三步走：分解->>解决->>合并MergeSort(arr, first, mid);MergeSort(arr, mid+1, last);Merge(arr, first, mid, last);}}int main(int argc, char* argv[]){int len = 15;int* arr = new int[len];randArr(arr, len, 100);printf("before sort:/n");printArr(arr, len);MergeSort(arr, 0, len-1);printf("/nafter mergeSort:/n");printArr(arr, len);printf("/n"); // 释放动态内存空间 delete arr;return 0;}

 

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参考维基百科 http://www.google.com.hk/url?q=http://zh.wikipedia.org/wiki/%25E5%25BD%2592%25E5%25B9%25B6%25E6%258E%2592%25E5%25BA%258F&sa=U&ei=2zUFTsX_BOSdmQW0tKDKDQ&ved=0CA4QFjAA&usg=AFQjCNHC05Ezfw-Px0x2CnRNVDLCwwIkJw