uva 10004 Bicoloring（判断一个图是否是二分图）

#include<cstdio>
#include<cstring>
#include<iostream>
#include<queue>
using namespace std;
int col[205],n,m;
bool map[205][205],flag;

bool bfs(int s)
{
    queue<int>q;
    q.push(s);
    col[s]=1;
    int i;
    while(!q.empty())
    {
        int p=q.front();
        q.pop();
        for(i=1;i<=n;++i)
        {
            if(map[p][i]&&col[i]==-1)
            {
                q.push(i);
                col[i]=!col[p];
            }
            else if(map[p][i]&&col[p]==col[i]) return 0;
        }
    }
    return 1;
}
int main()
{
    int i;
    while(scanf("%d",&n)!=EOF&&n>0)
    {
        scanf("%d",&m);
        memset(map,0,sizeof(map));
        memset(col,-1,sizeof(col));
        for(i=1;i<=m;++i)
        {
            int x,y;
            scanf("%d %d",&x,&y);
            map[x][y]=map[y][x]=1;
        }
        flag=1;
        for(i=0;i<n;++i)
            if(col[i]==-1&&!bfs(i))
            {
                flag=0;
                break;
            }
        if(flag) puts("BICOLORABLE.");
        else puts("NOT BICOLORABLE.");
    }
    return 0;
}

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int M[205][205],color[205],n;
bool bi(int u){

    for(int i=0;i<n;++i){
        if(M[u][i]){
            if(!color[i])
            {
                color[i]=3-color[u];
                if(!bi(i)) return 0;
            }
            else if(color[i]==color[u]) return 0;
        }
    }
    return 1;
}
int main()
{
    int i,m,x,y;
    while(~scanf("%d",&n)&&n){
        scanf("%d",&m);
        memset(M,0,sizeof(M));
        for(i=0;i<m;++i) {
            scanf("%d%d",&x,&y);
            M[x][y]=M[y][x]=1;
        }
        memset(color,0,sizeof(color));
        bool flag=1;
        for(i=0;i<n&&flag;++i)
            if(!color[i]){
                color[i]=1;
                if(!bi(i)) flag=0;
            }
        if(flag) puts("BICOLORABLE.");
        else puts("NOT BICOLORABLE.");
    }
    return 0;
}