排序算法总结（三）逆序对

求数组中的逆序对

#include<iostream>using namespace std;int MergeArray(int r[],int s,int m,int e,int temp[]){int i=m,j=e,count=0,k=0;while(i>=s&&j>=m+1){if (r[i]>r[j]){temp[k]=r[i];k++;count=count+(j-m);i--;}else if (r[i]<=r[j]){temp[k]=r[j];k++;j--;}}while(i>=s)//表示前半段数组中还有元素未放入临时数组    {        temp[k++]=r[i--];    }    while(j>m)    {        temp[k++]=r[j--];    }for(int z=0;z<k;z++){r[e-z]=temp[z];}return count;}int Nixudui(int r[],int s,int e,int temp[]){int count=0;if(s<e){//递归的界限int m=(s+e)/2;count+=Nixudui(r,s,m,temp);count+=Nixudui(r,m+1,e,temp);count+=MergeArray(r,s,m,e,temp);}return count;}void main(){int A[4]={7,5,6,4};int *temp=new int[4];int rs;rs=Nixudui(A,0,3,temp);delete[] temp;cout<<rs<<endl;system("pause");}