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  1. #include <unordered_set>
  2. #include <iostream>
  3.  
  4. struct Point {
  5.     int X, Y;
  6.  
  7.     Point() : X(0), Y(0) {};
  8.     Point(const int x, const int y) : X(x), Y(y) {};
  9. };
  10.  
  11. int main() {
  12.     auto hash = [](const Point& p) { return std::hash<int>()(p.X) * 31 + std::hash<int>()(p.Y); };
  13.     auto equal = [](const Point& p1, const Point& p2) { return p1.X == p2.X && p1.Y == p2.Y; };
  14.     std::unordered_set<Point, decltype(hash), decltype(equal)> mySet(8, hash, equal);
  15.  
  16.     Point a, b(1, 2), c(b), d(3, 4);
  17.  
  18.     mySet.emplace(a);
  19.     mySet.emplace(b);
  20.     mySet.emplace(c);  // Insertion fails; element already exists.
  21.     c = d;
  22.     mySet.emplace(c);
  23.     mySet.emplace(1, 1);
  24.  
  25.     for (auto const& pt : mySet) {
  26.         std::cout << "(" << pt.X << ", " << pt.Y << ")" << std::endl;
  27.     }
  28.  
  29. 	return 0;
  30. }
Success #stdin #stdout 0s 4548KB
comments (?)
stdin 
Standard input is empty
stdout 
(1, 1)
(3, 4)
(1, 2)
(0, 0)
https://ideone.com/ZA6IKr
language:
C++ (gcc 8.3)
created:
5 years ago
visibility:
secret

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