图的两种存法

#include <bits/stdc++.h>
using namespace std;

int main() {
vector<vector<int>>g(4);
for(auto [u,v]:vector<pair<int,int>>{{1,2},{2,3}}){g[u].push_back(v);g[v].push_back(u);}
cout<<g[2].size()<<" "<<g[1].size()+g[2].size()+g[3].size();
}

#include <bits/stdc++.h>
using namespace std;

int main() {
vector<vector<int>>g(4);
for(auto [u,v]:vector<pair<int,int>>{{1,2},{2,3}}){g[u].push_back(v);g[v].push_back(u);}
cout<<g[2].size()<<" "<<g[1].size()+g[2].size()+g[3].size();
}