Codeforces Round #553 (Div. 2) D. Stas and the Queue at the Buffet 贪心+公式转化

 1 #include<bits/stdc++.h>
 2 #define FOR(i,f_start,f_end) for(int i=f_start;i<=f_end;i++)
 3 #define MS(arr,arr_value) memset(arr,arr_value,sizeof(arr)) 
 4 #define F first 
 5 #define S second
 6 #define pii pair<int ,int >
 7 #define mkp make_pair
 8 #define pb push_back
 9 #define arr(zzz) array<ll,zzz>
10 using namespace std;
11 #define ll long long 
12 const int maxn=3e5+5;
13 const int inf=0x3f3f3f3f;
14 vector<pii>v;
15 int main(){
16     int n;
17     scanf("%d",&n);
18     for(int i=0;i<n;i++){
19     int a,b;    
20         scanf("%d%d",&a,&b);
21         v.pb(mkp(a,b));
22     }
23     sort(v.begin(),v.end(),[&](pii a,pii b)->bool{
24     return a.F-a.S>b.F-b.S;        
25     });
26     ll ans=0;
27 
28     for(int i=0;i<n;i++){
29         ans+=1ll*v[i].F*(i)+1ll*v[i].S*(n-i-1);
30     }
31     cout<<ans<<endl;
32 
33     return 0;
34 }