Codeforces Round #553 (Div. 2) D

题解：

就是从小到大对（ai-bi）进行排序

#include 
using namespace std;
typedef long long ll;
const int inf = 0x3f3f3f3f;
const int mod = 1e9 + 7;
const int N = 1e5 + 10;
struct node{
    int a,b,t;
} a[N];
bool cmp(node p1,node p2){
    return p1.t>p2.t;
}
int main(){
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    int n; cin>>n;
    for(int i=1;i<=n;i++) 
    cin>>a[i].a>>a[i].b, a[i].t = a[i].a-a[i].b;
    sort(a+1,a+1+n,cmp);
    ll ans = 0;
    for(int i=1;i<=n;i++){
        ans += 1ll * (a[i].a-a[i].b) * i + 1ll * a[i].b * n - a[i].a;
    }
    cout<