// test.cpp: 定义控制台应用程序的入口点。//#include "stdafx.h"#include
     
      #include 
      
       using namespace std;int sum;int *b;void merge_sort(int a[], int low, int high);void merge(int a[], int low, int mid, int high);void merge_sort(int a[],int low,int high) {     int mid;     if (low < high) {         mid = (low + high) / 2;         merge_sort(a, low, mid);         merge_sort(a, mid + 1, high);         merge(a, low, mid, high);     }  } void merge(int a[], int low, int mid, int high) {     int i = low;     int j = mid + 1;     int k = 0;     while (i <= mid && j <= high) {         if (a[i] <= a[j])             b[k++] = a[i++];         else {             b[k++] = a[j++];             sum += (mid - i + 1);//此处重难点 画图思考         }     }     while (i <= mid) {         b[k++] = a[i++];     }     while (j <= high) {         b[k++] = a[j++];     }     for (k = 0, i = low; i <= high; i++, k++) {         a[i] = b[k];     } } int main(){    int n, i=0, temp;    int a[10000];    cin >> n;    sum = 0;    b = new int[n];    while(cin >> temp && cin.get() != '\n')a[i++] = temp;    merge_sort(a, 0, n - 1);    delete[] b;    cout << sum << endl;  return 0;}