I - Balancing Act POJ - 1655

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<sstream>
#include<algorithm>
#include<queue>
#include<deque>
#include<iomanip>
#include<vector>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<fstream>
#include<memory>
#include<list>
#include<string>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
#define MAXN 200099
#define L 31
#define INF 1000000009
#define eps 0.00000001
#define sf(a) scanf("%d",&a)
/*
dp[i] 记录i点除去偶的最大点集点数
sum[i] 记录所有子节点数目
*/
struct edge
{
    int to, next;
}E[MAXN];
int sum[MAXN], dp[MAXN], head[MAXN];
int t, n, cnt;
void addedge(int f,int t)
{
    E[cnt].to = t;
    E[cnt].next = head[f];
    head[f] = cnt++;
}
void init()
{
    memset(sum, 0, sizeof(sum));
    memset(dp, 0, sizeof(dp));
    memset(head, -1, sizeof(head));
    cnt = 0;
}
void dfs(int u, int pre)
{
    sum[u] = dp[u] = 1;
    for (int i = head[u]; i != -1; i = E[i].next)
    {
        int v = E[i].to;
        if (v == pre) continue;
        dfs(v, u);
        sum[u] += sum[v];
        dp[u] = max(dp[u], sum[v]);
    }
    dp[u] = max(dp[u], n - sum[u]);
}
int main()
{
    sf(t);
    while (t--)
    {
        init();
        sf(n);
        for (int i = 0; i < n - 1; i++)
        {
            int a, b;
            sf(a), sf(b);
            addedge(a, b);
            addedge(b, a);
        }
        dfs(1, -1);
        int ans = INF, k = -1;
        for (int i = 1; i <= n; i++)
        {
            if (dp[i] < ans)
            {
                k = i, ans = dp[i];
            }
        }
        printf("%d %d\n", k, ans);
    }
}