timus 1106 Two Teams(二部图)

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <time.h>
#include <string>
#include <map>
#include <stack>
#include <vector>
#include <set>
#include <queue>
#define inf 10000000
#define mod 10000
typedef long long ll;
using namespace std;
const int N=105;
const int M=50000;
int power(int a,int b,int c){int ans=1;while(b){if(b%2==1){ans=(ans*a)%c;b--;}b/=2;a=a*a%c;}return ans;}
int color[N], vis[N];     
vector<int> G[N];
void dfs(int u)
{
    vis[u] = 1;
    for (int i = 0; i < G[u].size(); ++i)
    {
        int v = G[u][i];
        if (!vis[v])
        {
            color[v] = 3 - color[u];
            dfs(v);
        }
    }
}
int main()
{
    int n, t;
    scanf("%d", &n);
    for (int i = 1; i <= n; ++i)
        while (scanf("%d", &t) && t)
        {
            G[i].push_back(t);
        }
    memset(vis, 0, sizeof(vis));
    memset(color, 0, sizeof(color));
    for (int i = 1; i <= n; ++i)
        if (!vis[i])
        {
            color[i]=1;                
            dfs(i);
        }
    int sum = 0;
    for (int i = 1; i <= n; ++i)
        if (color[i] == 1)
            ++sum;
    printf("%d\n", sum);
    for (int i = 1; i <= n; ++i)
        if (color[i] == 1)
            printf("%d ", i);
    return 0;
}