hdu - 1829 - A Bug's Life

题意：判断一个图是否为二分图。

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1829

——>>直接dfs。

#include<cstdio>
#include<cstring>
#include<vector>

using namespace std;

const int maxn = 2000 + 10;
int color[maxn], n, m;
bool vis[maxn];
vector<int> G[maxn];

bool dfs(int u)     //判断u的在的连通分支是否为二分图
{
    vis[u] = 1;
    int i, len = G[u].size();
    for(i = 0; i < len; i++)
    {
        int v = G[u][i];
        if(color[u] == color[v]) return false;
        if(!color[v])
        {
            color[v]= 3 - color[u];
            if(!dfs(v)) return false;
        }
    }
    return true;
}

int main()
{
    int cnt = 1, T, i, x, y;
    scanf("%d", &T);
    while(T--)
    {
        scanf("%d%d", &n, &m);
        for(i = 0; i <= n; i++) G[i].clear();
        for(i = 1; i <= m; i++)
        {
            scanf("%d%d", &x, &y);
            G[x].push_back(y);
            G[y].push_back(x);
        }
        memset(color, 0, sizeof(color));
        memset(vis, 0, sizeof(vis));
        printf("Scenario #%d:\n", cnt++);
        bool ok = 1;
        for(i = 1; i <= n; i++)
        {
            if(!vis[i])
            {
                color[i] = 1;
                if(!dfs(i))
                {
                    ok = 0;
                    break;
                }
            }
        }
        if(ok) printf("No suspicious bugs found!\n\n");
        else printf("Suspicious bugs found!\n\n");
    }
    return 0;
}