백준 1764 : 듣보잡

https://www.acmicpc.net/problem/1764

1764번: 듣보잡

 

해싱 해싱 해싱을할까요

#include <iostream>
#include <unordered_map>
#include <string>
#include <vector>
#include <algorithm>
 
int N, M;
std::unordered_map<std::string, int> unknownList;
 
std::vector<std::string> ans;
 
void input()
{
    std::cin >> N >> M;
    std::string input;
    for (int i = 0; i < N; ++i)
    {
        std::cin >> input;
        unknownList[input] += 1;
    }
    for (int i = 0; i < M; ++i)
    {
        std::cin >> input;
        unknownList[input] += 2;
        if (unknownList[input] == 3)
        {
            ans.push_back(input);
        }
    }
}
 
int main()
{
    std::cin.tie(0);
    std::cin.sync_with_stdio(false);
    std::cout.tie(0);
    std::cout.sync_with_stdio(false);
    input();
    std::cout << ans.size() << '\n';
    std::sort(ans.begin(), ans.end());
    for (auto& it : ans)
    {
        std::cout << it << '\n';
    }
    return 0;
}

C++ unordered map의 성능은 날이 갈수록 좋아지고 있다고 한다...