基础图论3

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<set>
#include<algorithm>
#include<map>
#define maxn 10005
using namespace std;
vector<int>G[maxn];
int v;
int color[maxn];
bool dfs(int v,int c)
{
    color[v]=c;
   //cout<<G[v].size();
     for(int i=0;i<G[v].size();i++)
     {
         //cout<<color[G[v][i]]<<" "<<G[v][i]<<endl;
         if(color[G[v][i]]==c)return false;
         if(color[G[v][i]]==0&&!dfs(G[v][i],-c))return false;
     }
     return true;
}
void solve(int v){
    //cout<<"a"<<endl;
    for(int i=0;i<v;i++)
    {
        if(color[i]==0){
               // cout<<"a"<<endl;
        if(dfs(i,1)==true)
        {
            cout<<"yes"<<endl;
            return ;
        }
        }
    }
    cout<<"no"<<endl;
}
int main()
{
    int v,e;
    cin>>v>>e;
    memset(color,0,sizeof(color));
    for(int i=0;i<e;i++)
    {
        int s,t;
        cin>>s>>t;
        G[s].push_back(t);
        G[t].push_back(s);
    }
   // cout<<G[0].size();
    solve(v);
    return 0;
}