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  1. #include <iostream>
  2. #include <vector>
  3. #include <string>
  4. #include <algorithm>
  5.  
  6. std::vector<std::pair<int,std::string>> cities;
  7.  
  8. void add_city(const std::string &name, int pop) {
  9. 	if (cities.empty()) {
  10. 		cities.emplace_back(pop, name);
  11. 	}
  12. 	else {
  13. 		cities.emplace_back(pop + cities.back().first , name);
  14. 	}
  15. }
  16.  
  17. int total_population() {
  18.     return cities.empty() ? 0 : cities.back().first;
  19. }
  20.  
  21. const std::string select_city() {
  22. 	const int total = total_population();
  23. 	const int pos = std::rand() % total;
  24. 	const auto iter = std::lower_bound(begin(cities), end(cities), std::make_pair(pos, std::string()));
  25. 	return iter->second;
  26. }
  27.  
  28. int main() {
  29.  
  30. 	add_city("A",   50);
  31. 	add_city("B",  500);
  32. 	add_city("C",  1000);
  33.  
  34. 	for (unsigned i=0; i<15; ++i) {
  35. 		const std::string city = select_city();
  36. 		std::cout << city << ' ';
  37. 	}
  38.  
  39. 	return 0;
  40. }
Success #stdin #stdout 0s 3476KB
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stdin
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Standard input is empty
stdout
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C A B C B B B C C C C C B B C
https://ideone.com/XRV0DX
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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