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  1. #include <iostream>
  2. #include <algorithm>
  3. #include <vector>
  4.  
  5. using namespace std;
  6.  
  7. long double I[4];
  8.  
  9. #define QC Q.begin(),Q.end(),cmp
  10.  
  11. typedef pair<long double,unsigned long long> pdi;
  12.  
  13. unsigned long long Factor[21];
  14.  
  15. bool cmp(pdi a,pdi b){
  16.     return a.first > b.first;
  17. }
  18.  
  19. int main()
  20. {
  21.     int N;
  22.     cin >> N;
  23.     Factor[0] = 1;
  24.     for (int i=1;i<=20;i++)
  25.         Factor[i] = Factor[i-1]*i;
  26.     vector <pdi> Q;
  27.     for (int i=0;i<4;i++)
  28.         cin >> I[i];
  29.     long double p1 = 1;
  30.     for (int i=0;i<=N;i++){
  31.         long double p2 = 1;
  32.         for (int j=0;j<=N-i;j++){
  33.             long double p3 = 1;
  34.             for (int k=0;k<=N-i-j;k++){
  35.                 long double pp = p1*p2*p3;
  36.                 for (int z=0;z<N-i-j-k;z++)
  37.                     pp*=I[3];
  38.                 Q.push_back( pdi(pp, Factor[N]/Factor[i]/Factor[j]/Factor[k]/Factor[N-i-j-k] ) );
  39.                 p3*=I[2];
  40.             }
  41.             p2 *= I[1];
  42.         }
  43.         p1 *= I[0];
  44.     }
  45.     make_heap(QC);
  46.     long double predval = 0;
  47.     long double ans = 0;
  48.     while (!Q.empty()){
  49.  
  50.         pop_heap(QC);
  51.         pdi PRED = Q[Q.size() - 1];
  52.         Q.pop_back();
  53.         if (predval){
  54.             Q.push_back( pdi(predval + PRED.first ,1) );
  55.             push_heap(QC);
  56.             ans += predval + PRED.first;
  57.             PRED.second --;
  58.         }
  59.         ans += (PRED.second/2*2+0.0) * PRED.first;
  60.         if (PRED.second > 1){
  61.             Q.push_back( pdi(2.0*PRED.first ,PRED.second/2) );
  62.             push_heap(QC);
  63.         }
  64.         if (PRED.second & 1)
  65.             predval = PRED.first;
  66.         else predval = 0;
  67.     }
  68.     cout << ans;
  69.     return 0;
  70. }
Success #stdin #stdout 0s 3280KB
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https://ideone.com/MmpMwF
language:
C++ (gcc 8.3)
created:
8 years ago
visibility:
secret

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