Submission #1363293

#TimeUsernameProblemLanguageResultExecution timeMemory
1363293yyc000123Social Engineering (EGOI22_socialengineering)C++20
0 / 100
167 ms30348 KiB
#include<bits/stdc++.h>
using namespace std ;
#define F first
#define S second
const int N = 2e5+5 ;
const int M = 4e5+5 ;
int n , m , vis[M] , vis1[N] , vis2[N] ;
vector<pair<int,int>> nei[N] ;
vector<int> path ;

int GetMove(){
    int ret ; cin >> ret ; return ret ;
}
void MakeMove(int v){
    cout << v << endl ;
}

bool checkdfs(int node){
    vis1[node] = 1 ;
    for(auto it:nei[node]){
        if(vis[it.S]) continue ;
        if(it.F==1){
            vis2[node] = 1 ; vis1[node] = 0 ; return true ;
        }
        if(vis1[it.F]) continue ;
        vis[it.S] = 1 ;
        if(checkdfs(it.F)){
            vis1[node] = 0 ; return true ;
        }
        vis[it.S] = 0 ;
    }
    vis1[node] = 0 ;
    return false ;
}

bool check(){
    for(auto it:nei[1]){
        if(vis[it.S] || vis2[it.F]) continue ;
        vis[it.S] = 1 ; vis2[it.F] = 1 ;
        if(!checkdfs(it.F)) return false ;
    }
    return true ;
}

bool dfs(int node){
    path.push_back(node) ;
    if(node==1) return true ;
    for(auto it:nei[node]){
        if(vis[it.S]) continue ;
        vis[it.S] = 1 ;
        if(dfs(it.F)) return true ;
        vis[it.S] = 0 ;
    }
    path.pop_back() ;
    return false ;
}

int main(){
    cin >> n >> m ;
    for(int i=0 ; i<m ; i++){
        int u , v ; cin >> u >> v ;
        nei[u].push_back({v,i}) ; nei[v].push_back({u,i}) ;
    }
    if(!check()){
        cout << "NO" << endl ;
        return 0 ;
    }
    cout << "YES\n" ;
    memset(vis,0,sizeof(vis)) ;
    while(true){
        int temp = GetMove() ;
        if(!temp) break ;
        for(auto it:nei[1]){
            if(it.F==temp) vis[it.S] = 1 ;
        }
        bool flag = dfs(temp) ;
        assert(flag) ; //
        for(int i=1 ; i<path.size() ; i++) MakeMove(path[i]) ;
    }
}
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