#include<iostream>
#include<algorithm>
#include<cstdio>
#include<queue>
#include<cstring>
#define maxn 1005
#define inf 0x3f3f3f3f
using namespace std;
int n;
int first[maxn],nxt[maxn],to[maxn],e;
int color[maxn];
void add(int u,int v){
to[e]=v;
nxt[e]=first[u];
first[u]=e++;
}
bool bfs(int u,int c){
queue<int>q;
q.push(u);
color[u]=c;
while(!q.empty()){
int u=q.front();
q.pop();
for(int i=first[u];~i;i=nxt[i]){
int v=to[i];
if(color[v]==color[u])return false;
if(color[v]==0){
color[v]=-color[u];
q.push(v);
}
}
}
return true;
}
bool dfs(int u,int c)
{
color[u]=c;
for(int i=first[u];~i;i=nxt[i]){
int v=to[i];
if(color[u]==color[v])return false;
if(!color[v]){
if(!dfs(v,-c))return false;
}
}
return true;
}
int main()
{
int m;
int u,v;
freopen("in.txt","r",stdin);
while(scanf("%d%d",&n,&m)!=EOF){
memset(color,0,sizeof color);
memset(first,-1,sizeof first);
for(int i=0;i<m;i++){
scanf("%d%d",&u,&v);
add(u,v);
add(v,u);
}
if(bfs(0,1))
//if(dfs(0,1))
printf("%d\n",1);
else puts("0");
}
}二分图的判定模板(dfs,bfs)
原文：http://blog.csdn.net/u013497977/article/details/43835805
