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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long
  4. #define FAST1 ios_base::sync_with_stdio(false);
  5. #define FAST2 cin.tie(NULL);
  6.  
  7. bool sort_on_second(pair<ll,ll> left, pair<ll,ll> right){
  8.     return left.second<right.second;
  9. }
  10. void solve(){
  11.     ll n;
  12.     cin>>n;
  13.     vector<pair<ll,ll>> arr(n);
  14.     ll ans=0;
  15.     for(ll i=0;i<n;i++)
  16.     {
  17.         cin>>arr[i].first>>arr[i].second;
  18.         ans+=2*arr[i].first;
  19.     }
  20.     sort(arr.begin(),arr.end(),sort_on_second);
  21.     reverse(arr.begin(),arr.end());
  22.     ll i=0,j=n-1;
  23.     ll cur =0;
  24.     while(i<=j){
  25.         ll tar=arr[j].second;
  26.         if(i==j){
  27.             ll can_take=arr[i].first;
  28.             ll to_take=max(0ll,arr[i].second-cur);
  29.             can_take=max(0ll,can_take-to_take);
  30.             ans-=can_take;
  31.             break;
  32.         }
  33.         else if(cur>=tar){
  34.             cur+=arr[j].first;
  35.             ans-=arr[j].first;
  36.             j--;
  37.         }
  38.         else if(cur+arr[i].first<=arr[j].second){
  39.             cur+=arr[i].first;
  40.             arr[i].first=0;
  41.             i++;
  42.         }
  43.         else{
  44.             ll to_take=arr[j].second-cur;
  45.             cur+=to_take;
  46.             cur+=arr[j].first;
  47.             arr[i].first-=to_take;;
  48.             ans-=arr[j].first;
  49.             j--;
  50.         }
  51.     }
  52.     cout<<ans<<endl;
  53.  
  54. }
  55.  
  56. int main(){
  57.     FAST1;
  58.     FAST2;
  59.     ll t=1;
  60.     while(t--){
  61.         solve();
  62.     }
  63. }
  64.  
Success #stdin #stdout 0s 5676KB
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https://ideone.com/JoxG94
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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