归并排序算法

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自己想找找归并排序怎么实现的，结果在网上居然没找到一个能用的归并排序的算法，经过自己的琢磨，现在写出了下面的算法。

void MergeArray(int *a,int first,int middle,int last){int n1 = middle-first;int n2 = last - middle-1;//注意此处的长度int *L = new int[n1+1];int *R = new int[n2+1];int i , j ,k;for(i = 0;i<=n1;i++)L[i] = a[first+i];for(j = 0;j<=n2;j++)R[j] = a[middle+j+1];k = 0,i=0,j=0;while(i<=n1 &&j<=n2){if(L[i]<R[j])a[first+i+j] = L[i++];elsea[first+i+j] = R[j++];}while(i<=n1){a[first+i+j] = L[i++];}while(j<=n2){a[first+i+j] = R[j++];}delete []L;delete []R;}void mergesort(int *a, int first, int last)  {  if(first>=last)return;    if(first<last){int mid = (first + last) / 2;          mergesort(a, first, mid);    //左边有序          mergesort(a, mid + 1, last); //右边有序          MergeArray(a, first, mid, last); //再将二个有序数列合并 }}void MergeSort(int *a, int n)  {      mergesort(a,0,n-1); } void PrintArray(int *b){for(int i = 0;i<10;i++){cout<<b[i]<<"  ";}cout<<endl;}int main(){int a[10];for(int k = 0;k<5;k++){for(int i = 0;i<10;i++){a[i] = rand()%100;}cout<<"排序前：";PrintArray(a);//QSort(a,0,9);MergeSort(a,10);cout<<"排序后：";PrintArray(a);cout<<endl;}return 0;}

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