C++ 归并排序实现（算法导论）

#include <iostream>using namespace std;void merge(int *data, int p, int q, int r){int n1, n2, i, j, k; int *left=NULL, *right=NULL; n1 = q-p+1; n2 = r-q; left = (int *)malloc(sizeof(int)*(n1)); right = (int *)malloc(sizeof(int)*(n2)); for(i=0; i<n1; i++) //对左数组赋值left[i] = data[p+i]; for(j=0; j<n2; j++) //对右数组赋值right[j] = data[q+1+j]; i = j = 0; k = p; while(i<n1 && j<n2) //将数组元素值两两比较，并合并到data数组 {if(left[i] <= right[j])data[k++] = left[i++];elsedata[k++] = right[j++]; } for(; i<n1; i++) //如果左数组有元素剩余，则将剩余元素合并到data数组data[k++] = left[i]; for(; j<n2; j++) //如果右数组有元素剩余，则将剩余元素合并到data数组data[k++] = right[j];} void mergeSort(int *data, int p, int r){ int q; if(p < r) //只有一个或无记录时不须排序 {q = (int)((p+r)/2); //将data数组分成两半 mergeSort(data, p, q); //递归拆分左数组mergeSort(data, q+1, r); //递归拆分右数组merge(data, p, q, r); //合并数组 }}int main() { int n; int* input = NULL; //输入数据 cout<<"请输入数组的长度: "; cin>>n;input = (int *)malloc(sizeof(int)*(n)); cout<<"请对数组赋值: "; for(int i=0; i<n; ++i) { cin>>input[i]; } //处理数据 mergeSort(input,0,n-1); //输出结果 for(int i=0; i<n; ++i) cout<<input[i]<<" "; cout<<endl; system("pause"); return 0; }