A Good Game

A Good Game

维护前缀和，排序

#include<bits/stdc++.h>
using namespace  std;
typedef long long ll;
#define maxn 100004
ll sum[maxn];
vector<ll>v;
int main()
{
    int t;
    int n,m;
    scanf("%d",&t);
    while(t--){
        
        scanf("%d%d",&n,&m);
        ll t;
        v.clear();
        for(int i=1;i<=n;i++){
            scanf("%lld",&t);
            sum[i]=sum[i-1]+t;
        }
        int a,b;
        for(int i=1;i<=m;i++){
            scanf("%d%d",&a,&b);
            v.push_back(sum[b]-sum[a-1]);
        }
        sort(v.begin(),v.end());
        ll ans=0;
        for(int i=0;i<m;i++){
            ans+=(i+1)*v[i];
        }
        cout<<ans<<'\n';
    }
}