Submission #2522288

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Source Code Expand

#include <iostream>
#include <stdio.h>
#include <stack>
#include <queue>
#include <algorithm>
#include <set>
#include <math.h>
#include <iomanip>
#include <vector>
using namespace std;
#define ll long long
#define rep(i,n) for(ll i=0;i<n;++i)
#define Sort(a) sort(a.begin(),a.end())
#define Reverse(a) reverse(a.begin(),a.end())
vector<ll>node[100600];
ll N,M;
bool come[100600];
int came;
int hen;
void _DFS(int x,int bef){
    if(come[x]){came= -1000000000;return;}
    come[x]=true;
    came++;
    rep(i,node[x].size()){
       if(node[x][i]==bef){continue;}
        hen++;
        _DFS(node[x][i],x);
    }
}
void DFS(int x){
    _DFS(x,-1);
}
int main(){
	cin>>N>>M;
    rep(i,M){
        int u,v;
        cin>>u>>v;
        u--;v--;
        node[u].push_back(v);
        node[v].push_back(u);
    }
    int ans=0;
    fill(come,come+N,false);
    for(int i=0;i<N;i++)
    {
        if(!come[i]){
             ans++;
            hen=came=0;
            DFS(i);
             if(hen!=came-1){ans--;}
        }
    }
    cout<<ans<<endl;
    return 0;
}

Submission Info

Judge Result