poj 3352【Road Construction】

狂晕，是我做题太少了吧？我竟然直接按输入输出的模式做题，即输出“Output for Sample Input 1”，呜呜，WA了几次就是因为这个。。。。。。。。。。。。。。。。。。。。。。。。。。。

#include <iostream>
#include <vector>
#include <cstring>
#include <algorithm>
using namespace std;

const int maxN = 1000+10;
int low[maxN];
int DFN[maxN];
int cnt;
int Branch;
int degree[maxN];

vector<int> edge[maxN];

void Tarjan(int x,int fa)
{
    low[x] = DFN[x] = cnt ++;

    int len = edge[x].size();
    for(int i = 0;i < len;i ++)
    {
        int u = edge[x][i];
        if(u == fa) continue;
        if(!DFN[u])
        {
            Tarjan(u,x);
            low[x] = min(low[x],low[u]);
        }
        else if(low[x] > DFN[u])
            low[x] = DFN[u];
    }
}

void UseTarjan(int n)
{
    memset(DFN,0,sizeof(DFN));
    cnt = 1;

    Branch = 0;
    for(int i = 1;i <= n;i ++)
    {
        if(!DFN[i])
        {
            Tarjan(i,i);
            Branch ++;
        }
    }
}

int main()
{
    int n,m;

    while(cin >> n >> m)
    {
        for(int i = 0;i <= n;i ++) edge[i].clear();

        for(int i = 0;i < m;i ++)
        {
            int u,v;
            cin >> u >> v;
            edge[u].push_back(v);
            edge[v].push_back(u);
        }

        UseTarjan(n);

        memset(degree,0,sizeof(degree));
        for(int i = 1;i <= n;i ++)
        {
            int len = edge[i].size();
            for(int j = 0;j < len;j ++)
            {
                if(low[i] != low[edge[i][j]])
                    degree[low[i]] ++;
            }
        }

        int ans = 0;
        for(int i = 1;i < cnt;i ++)
        {
            if(degree[i] == 1) ans ++;
        }
        ans = (ans + 1) / 2;
        cout << ans << endl;
    }

    return 0;
}