归并排序

/*¹é²¢ÅÅÐò*/#include <iostream>using namespace std;void mergeall(int a[],int first,int mid,int end,int t[]){int i = first;int j = mid+1;int k =0;while(i<= mid && j <= end){if(a[i] <= a[j]){t[k++] = a[i++];}else{t[k++] = a[j++];}}while(j <= end){t[k++] = a[j++]; }while(i <= mid){t[k++] = a[i++];}for(int m = 0;m <k;m++){a[first+m] = t[m];}}void merge(int a[],int first,int end,int t[]){int mid = (first+end)/2;if(first<end){merge(a,first,mid,t);merge(a,mid+1,end,t);mergeall(a,first,mid,end,t);}}void mergefirst(int a[],int first,int end){int * t = new int[8];merge(a,first,end,t);delete []t;}void main(){int a[8] = {3,1,4,2,6,7,9,8};mergefirst(a,0,7);for(int i =0;i<8;i++){cout << a[i];}}

遇到的问题：

一开始没有mergefirst函数，直接在merge函数中new了一个动态数组，但是会导致debug error；

难点：

在于mergeall函数，采用直接插入的方法，复杂度为O(n).

参考：http://blog.csdn.net/morewindows/article/details/6678165