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  1. //#Ewise Electric
  2.  
  3. #include <bits/stdc++.h>
  4. using namespace std;
  5. #define ll long long
  6. bool ONE_CASE=true;
  7.  
  8. const ll OL=1e18;
  9. const double eps=1e-7;
  10. vector<pair<long double,long double>> neods;
  11. int n;
  12.  
  13. void solve(){
  14.     cin>>n;
  15.  
  16.     for(int i=0;i<n;i++){
  17.         int l,m;
  18.         cin>>l>>m;
  19.         neods.push_back({l,m});
  20.     }    
  21.     sort(neods.begin(),neods.end());
  22.     cout<<fixed<<setprecision(8);
  23.  
  24.     for(int i=0;i<n-1;i++){
  25.  
  26.         //we need to BS between l and r
  27.         long double l=neods[i].first,r=neods[i+1].first;
  28.         long double mid=(l+r)/2.0,x1=0,x2=0;
  29.             for(int z=i+1;z<n;z++){
  30.                 x2+=(neods[z].second)/(powl((neods[z].first-mid),2));
  31.             }
  32.             for(int z=0;z<=i;z++){
  33.                 x1+=(neods[z].second)/(powl((neods[z].first-mid),2));
  34.                 if(x1>x2+eps)break;
  35.             }
  36.         while(abs(x2-x1)>eps){
  37.  
  38.  
  39.             /*cout<<mid<<endl;
  40.             cout<<x2<<"#"<<x1<<endl;*/
  41.  
  42.             if(x2>x1){
  43.                 r=mid;
  44.             }
  45.             else{
  46.                 l=mid;
  47.             }
  48.             mid=(r+l)/2.0;
  49.             x1=x2=0;
  50.             for(int z=i+1;z<n;z++){
  51.                 x2+=(neods[z].second)/(powl((neods[z].first-mid),2));
  52.             }
  53.             for(int z=0;z<=i;z++){
  54.                 x1+=(neods[z].second)/(powl((neods[z].first-mid),2));
  55.                 if(x1>x2+eps)break;
  56.             }
  57.             /*cout<<mid<<endl;
  58.             cout<<x2<<"#"<<x1<<endl;*/
  59.         }
  60.  
  61.         cout<<mid<<endl;
  62.     }
  63. }
  64. int main(){
  65.     ios_base::sync_with_stdio(false);
  66.     cin.tie(NULL);
  67.  
  68.  
  69.  
  70.     int t=1;
  71.     if(!ONE_CASE)
  72.         cin>>t;
  73.     while(t--){
  74.  
  75.         solve();
  76.     }
  77. }
Success #stdin #stdout 0.01s 5420KB
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https://ideone.com/oRs18v
language:
C++14 (gcc 8.3)
created:
1 year ago
visibility:
secret

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