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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4.  
  5. // returns number of occurences of character c in string s
  6. int count_char(string &s, char c) {
  7.     return count(s.begin(), s.end(), c);
  8. }
  9.  
  10.  
  11. int main() {
  12.     string s = "00000000001111111111";            // red and white roses 
  13.     sort(s.begin(), s.end());
  14.  
  15.     int total_permutations = 0;
  16.     int count_in_church = 0;
  17.  
  18.  
  19.     // check next lexicographic permutation of s 
  20.     do {
  21.         total_permutations += 1;
  22.  
  23.         // check if bride steps into church by checking if
  24.         // the number of ones exceeds the number of zeros
  25.         int cnt_0 = 0;
  26.         int cnt_1 = 0;
  27.  
  28.         for (char c : s) {
  29.         	if (c == '0') {cnt_0 += 1;}
  30.         	else {cnt_1 += 1;}
  31.  
  32.         	if (cnt_1 > cnt_0) {
  33.         		count_in_church += 1;
  34.         		break;
  35.         	}
  36.         }
  37.  
  38.     } while(std::next_permutation(s.begin(), s.end()));
  39.  
  40.  
  41.     cout << "number of times bride entered church: " << count_in_church << '\n';
  42.     cout << "total permutations: " << total_permutations << '\n';
  43.     cout << "probability: " << 1.0 * count_in_church / total_permutations << '\n';
  44. }
Success #stdin #stdout 0s 15240KB
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stdin
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Standard input is empty
stdout
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number of times bride entered church: 167960
total permutations: 184756
probability: 0.909091
https://ideone.com/dNdQHH
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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