POJ 3107 Godfather树形dfs

http://poj.org/problem?id=3107

题意：给出n个点，n-1条边，去掉一个点(x)后形成的子树最多点  最小的点(x)

以前貌似做过，现在重新用树形dfs缕缕思路

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#define Max(a,b)a>b?a:b
#define Min(a,b)a<b?a:b
#define MAX 50005
using namespace std;
int head[MAX],mark[MAX],vs[MAX],sumVal[MAX],maxSub[MAX];
int n,s_edge,cnt,MIN;
struct Edge
{
    int to,nxt;
}edge[MAX*2];

void addedge(int u,int v)
{
    s_edge++;
    edge[s_edge].to=v;
    edge[s_edge].nxt=head[u];
    head[u]=s_edge;

    s_edge++;
    edge[s_edge].to=u;
    edge[s_edge].nxt=head[v];
    head[v]=s_edge;
}

void dfs(int x)
{
    vs[x]=1;
    sumVal[x]=1;
    maxSub[x]=0;
    for(int e=head[x];e;e=edge[e].nxt)
    {
        int v=edge[e].to;
        if(!vs[v])
        {
            dfs(v);
            sumVal[x]+=sumVal[v];
            maxSub[x]=Max(maxSub[x],sumVal[v]);
        }
    }
    int k;
    k=Max(n-sumVal[x],maxSub[x]);//这里 还出过错，最大中的最小、、、
    if(k==MIN)
      mark[cnt++]=x;
    else if(k<MIN)
    {
        MIN=k;
        cnt=0;
        mark[cnt++]=x;
    }
   return ;
}
int main()
{
        int i,a,b;
        scanf("%d",&n);

        memset(head,0,sizeof(head));
        s_edge=0;

        for(i=1;i<n;i++)
        {
            scanf("%d%d",&a,&b);
            addedge(a,b);
        }

        memset(vs,0,sizeof(vs));
        cnt=0;
        MIN=50010;
        dfs(1);
        sort(mark,mark+cnt);
        for(i=0;i<cnt;i++)
        {
            if(i==0) printf("%d",mark[i]);
            else printf(" %d",mark[i]);
        }
        printf("\n");

    return 0;
}