历届试题 小朋友排队

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <vector>
#include <algorithm>
#include <string>
#include <cmath>
#include <stack>
#include <map>
using namespace std;
const double clf =1e-8;
//const double e= 2.718281828;
const double PI = 3.141592653589793;
const long int MAX=1e9;
#define ll long long
//const int mx=20000+1;
//priority_queue<int > p;
priority_queue<int ,vector<int> , greater<int> > pq;
const int M = 1e5+5;
typedef struct kid{
    int h;
    int num;
} kids;
kids s[M],t[M];
void merger(int l,int r)
{
    if(l+1<r)
    {
        int mid = l+(r-l)/2;
        int q=l,p=mid,i=l;
        merger(l,mid);
        merger(mid,r);
        while(q<mid||p<r)
        {
            if(p>=r||(q<mid&&s[q].h<=s[p].h))
            {
                t[i]=s[q++];
                t[i].num+=p-mid;
            }
            else
            {
                t[i]=s[p];p++;
                t[i].num+=mid-q;
            }i++;
        }
        for(int i=l;i<r;i++)
            s[i]=t[i];
    }
}
int main()
{
    freopen("data.in","r",stdin);
    //freopen("data.out","w",stdout);
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++)
    {
        scanf("%d",&s[i].h);
        s[i].num=0;
    }
    merger(0,n);
    ll sum=0;
    for(int i=0;i<n;i++)
    {
        sum+=((1+s[i].num)*s[i].num)/2;
    }
    printf("%lld\n",sum);
    return 0;
}