归并排序求逆序数对。

#include <iostream>
#include <stdio.h>
#include <cstring>
#include <vector>
using namespace std;
int high[100010];
int temp[100010];
int angry[100010];
int num;
void mergesort(int first,int mid,int last)
{
    int left1=first,right1=mid,left2=mid+1,right2=last;
    int i=0;
    while(left1<=right1&&left2<=right2)
    {
        if(high[left1]<=high[left2])
        {
            temp[i++]=high[left1++];
        }
        else
        {
            temp[i++]=high[left2++];
            angry[left2]+=right1-left1+1;
            num+=right1-left1+1;
            for(int j=left1; j<=right1; j++)
            {
                angry[j]++;
            }

        }
    }
    if(left1>right1)
    {
        while(left2<=right2)
        {
            temp[i++]=high[left2++];
        }
    }
    else if(left2>right2)
    {
        while(left1<=right1)
        {
            temp[i++]=high[left1++];
        }
    }
    for(int i=0; i<last-first+1; i++)
    {
        high[first+i]=temp[i];
    }

}
void Sort(int first,int last)
{
    if(first<last)
    {
        int mid=(first+last)/2;
        Sort(first,mid);
        Sort(mid+1,last);
        mergesort(first,mid,last);
    }
}
int main()
{
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        num=0;
        for(int i=0; i<n; i++)
            scanf("%d",&high[i]);
        Sort(0,n-1);
        for(int i=0; i<n; i++)
        {
            printf("%d ",angry[i]);
        }
        cout<<endl;
        cout<<num<<endl;
    }

    return 0;
}