unordered_map_with_pair_test.cc

#include <unordered_map>
#include <map>
#include <iostream>

using namespace std;

struct myeq : std::binary_function<pair<int , int> , pair<int , int> , bool>{
  bool operator() (const pair<int , int> & x , const pair<int , int> & y) const{
    //keyの一致って普通これですよね
    return x.first == y.first && x.second == y.second;
  }
};

struct myhash : std::unary_function<pair<int , int> , size_t>{
private:
  const hash<int> h_int;
public:
  myhash() : h_int() {}
  size_t operator()(const pair<int , int> & p) const{
    //http://stackoverflow.com/questions/738054/hash-function-for-a-pair-of-long-long
    size_t seed = h_int(p.first);
    return h_int(p.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
  }
};

int main(){
  int sum  = 0;

  
  //一つめの数字が何してるのかわかってない
  myhash h;
  myeq   e;
  //unordered_map<pair<int , int> , int  , myhash , myeq> m(3 , h , e);
  unordered_map<pair<int , int> , int  , myhash , myeq> m(3);
  for(int i = 0; i <  1000; ++i){
    for(int j = 0; j <  1000; ++j){
      //m.insert(pair<pair<int,int> , int>(make_pair(i, j) , 1));
      m[make_pair(i, j)] = 1;
    }
  }

  for(int i = 0; i <  1000; ++i){
    for(int j = 0; j <  1000; ++j){
      sum += m[make_pair(i, j)];
    }
  }

  cout << sum << endl;
}