求数组中的逆序对

#include <iostream>using namespace std;int count = 0;void merge(int *a,int p,int q,int r){int n1 = q-p+1;int n2 = r-q;int *m = new int[n1];int *n = new int[n2];for(int i=0;i<n1;i++) m[i] = a[p+i];for(int j=0;j<n2;j++) n[j] = a[q+j+1];int i=0,j=0,k=p;while(i<n1&&j<n2){if(m[i]<=n[j]) a[k++] = m[i++];else {int ni = q + 1 + j - k;count += ni;a[k++] = n[j++];}}while(i<n1) a[k++] = m[i++];while(j<n2) a[k++] = n[j++];delete[] m,n;}void mergeSort(int *a,int p,int r){if(p<r){int q = (p+r)/2;mergeSort(a,p,q);mergeSort(a,q+1,r);merge(a,p,q,r);}}int main(int argc, char** argv) {int a[10] = {9,8,7,6,5,4,3,2,1,0};mergeSort(a,0,9);for(int i=0;i<10;i++)cout<<a[i];cout<<endl<<count<<endl;return 0;}