1137. Bus Routes 夜

http://acm.timus.ru/problem.aspx?space=1&num=1137

任何一个线路都是一个环  任意两个环如果有至少一个共同的节点 则两个环可以扩展成一个大的环

只要用dfs搜一遍记录路径就可以了

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<vector>
#include<map>
#include<queue>
#include<stack>
#include<cmath>
#define LL long long
//#pragma comment(linker, "/STACK:1024000000,1024000000")
using namespace std;

const int INF=0x3f3f3f3f;
//const int N=105;
const int M=1005;
const int L=10005;
vector<int>str[L];
vector<bool>visited[L];
vector<int>ans;
int a[M];
void dfs(int x,int k)
{
    for(unsigned int i=0;i<str[x].size();++i)
    {
        if(!visited[x][i])
        {
            visited[x][i]=true;
            ans.insert(ans.begin()+k,str[x][i]);
            dfs(str[x][i],k+1);
        }
    }
}
int main()
{
    //freopen("data.txt","r",stdin);

    int n;
    while(cin>>n)
    {
        int m;
        for(int i=1;i<L;++i)
        {str[i].clear();visited[i].clear();}
        int num=0;
        int st=-1;
        while(n--)
        {
            cin>>m;
            num+=m;
            for(int i=0;i<=m;++i)
            {
                cin>>a[i];
                if(st==-1)
                st=a[i];
                if(i)
                {
                    str[a[i-1]].push_back(a[i]);
                    visited[a[i-1]].push_back(false);
                }
            }
        }
        ans.clear();
        ans.push_back(st);
        dfs(st,1);
        if(num!=ans.size()-1)
        cout<<"0"<<endl;
        else
        {
            cout<<num;
            for(int i=0;i<ans.size();++i)
            cout<<" "<<ans[i];
            cout<<endl;
        }
    }
    return 0;
}