poj1655 Balancing Act

//Serene
#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#include<cmath>
using namespace std;
const int maxn=2e4+10;
int T,n,tot;

int aa;char cc;
int read() {
	aa=0;cc=getchar();
	while(cc<‘0‘||cc>‘9‘) cc=getchar();
	while(cc>=‘0‘&&cc<=‘9‘) aa=aa*10+cc-‘0‘,cc=getchar();
	return aa;
}

int fir[maxn],nxt[2*maxn],to[2*maxn],e=0;
void add(int x,int y) {
	to[++e]=y;nxt[e]=fir[x];fir[x]=e;
	to[++e]=x;nxt[e]=fir[y];fir[y]=e;
}

struct Node{
	int pos,fa,size,maxnum;
}node[maxn];

void dfs(int pos) {
	node[pos].pos=pos;
	node[pos].size=1;
	for(int y=fir[pos];y;y=nxt[y]) {
		if(to[y]==node[pos].fa) continue;
		node[to[y]].fa=pos;dfs(to[y]);
		node[pos].maxnum=max(node[pos].maxnum,node[to[y]].size);
		node[pos].size+=node[to[y]].size;
	}
}

bool cmp(const Node& a,const Node& b) {
	int x=max(a.maxnum,tot-a.size),y=max(b.maxnum,tot-b.size);
	return x!=y? x<y:a.pos<b.pos;
}

int main() {
	T=read();
	int x,y;
	while(T--) {
		memset(fir,0,sizeof(fir));e=0;
		memset(node,0,sizeof(node));
		n=read();
		for(int i=1;i<n;++i) {
			x=read();y=read();
			add(x,y);
		}
		dfs(1);tot=node[1].size;
		sort(node+1,node+n+1,cmp);
		x=max(node[1].maxnum,tot-node[1].size);
		printf("%d %d\n",node[1].pos,x);
	}
	return 0;
}