题解 | 【模板】链式前向星

#include <bits/stdc++.h>
using namespace std;
int main(){
    int a,b,cnt=0;
    cin>>a>>b;
    if(a==1){
        cout<<"None";
        return 0;
    }
    vector<deque<int>> cc(a+1,deque<int>(a+1));  
    while(b--){
        int aa,bb;
        cin>>aa>>bb;
        cc[aa].push_back(bb);cc[aa].pop_front();
        cc[bb].push_back(aa);cc[bb].pop_front();
    }
    for(int i=1;i<=a;i++){
        sort(cc[i].begin(),cc[i].end());
    }
    for(int i=1;i<=a;i++){
        for(int j=1;j<=a;j++){
            if(cc[i][j]==0)continue;
            cout<<cc[i][j]<<" ";cnt++;
        }
        if(cnt==0){
            cout<<"None";
        }
        cout<<endl;
        cnt=0;
    }
}