# poj1655

/***************************************************************\
*Author:Hu Wenbiao
*Created Time: Tue 17 Aug 2010 04:54:15 PM CST
*File Name: main.cpp
*Description:树状dp。邻接表
\***************************************************************/

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
/*----------------------*Global Variable*----------------------*/
int dp[20010], first[20010], tot, t, N, a, b;
struct Edge {
int next, to;
} edge[40010];
//*=======================*Main Program*=======================*//
using namespace std;

void insertedge(int a, int b)
{				//添加边(a,b),(b,a)
edge[tot].to = b;
edge[tot].next = first[a];
first[a] = tot++;
edge[tot].to = a;
edge[tot].next = first[b];
first[b] = tot++;
}

int tree_dp(int from, int now)
{				//现在结点now，它的父结点是from
//sum记录now为根的子树的结点数，_max记录now各个子树最大结点数
int p = first[now], to;
int _max = 0, sum = 1, tmp;
while (p != -1) {
to = edge[p].to;
p = edge[p].next;
if (to == from)
continue;
tmp = tree_dp(now, to);
if (_max < tmp)
_max = tmp;
sum += tmp;
}
dp[now] = N - sum > _max ? N - sum : _max;
return sum;
}

int main()
{
//freopen("input","r",stdin);
scanf("%d", &t);
while (t--) {
memset(first, -1, sizeof(first));
tot = 0;
scanf("%d", &N);
for (int i = 1; i < N; i++) {
scanf("%d%d", &a, &b);
insertedge(a, b);
}
tree_dp(0, 1);
int ans, _min = N;
for (int i = 1; i <= N; i++) {
if (dp[i] < _min) {
_min = dp[i];
ans = i;
}
}
printf("%d %d\n", ans, dp[ans]);
}
}


Source Code

posted @ 2010-08-17 18:24  open source  阅读(222)  评论(0编辑  收藏