【poj1655】Balancing Act

// poj1655
#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<cmath>
#define LL long long
#define inf 2147483640
#define Pi acos(-1.0)
#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);
using namespace std;

const int maxn=20010;
struct edge {int to,next;}e[maxn<<2];

int head[maxn],vis[maxn],son[maxn],cnt,size,ans,n;

void insert(int u,int v) {
    e[++cnt].to=v;e[cnt].next=head[u];head[u]=cnt;
    e[++cnt].to=u;e[cnt].next=head[v];head[v]=cnt;
}
void dfs(int x) {
    vis[x]=1,son[x]=0;
    int tmp=0;
    for (int i=head[x];i;i=e[i].next) if (!vis[e[i].to]) {
            dfs(e[i].to);
            son[x]+=son[e[i].to]+1;
            tmp=max(tmp,son[e[i].to]+1);
        }
    tmp=max(tmp,n-son[x]-1);
    if (tmp<size || (tmp==size && x<ans)) size=tmp,ans=x;
}
int main() {
    int T;scanf("%d",&T);
    while (T--) {
        scanf("%d",&n);
        memset(vis,0,sizeof(vis));memset(head,0,sizeof(head));
        cnt=ans=0;size=inf;
        for (int i=1;i<n;i++) {
            int u,v;
            scanf("%d%d",&u,&v);
            insert(u,v);
        }
        dfs(1);
        printf("%d %d\n",ans,size);
    }
    return 0;
}