#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
struct node {
int now, next;
} tree[40005];
int n, sum[40005], son[20005];
int head[20005], vis[20005], len;
//sum数组代表包含该节点与该点子节点数量和
//son数组代表该节点包含的所有子树的最大节点数
void add(int x, int y) { //建树
tree[len].now = y;
tree[len].next = head[x];
head[x] = len;//记录头节点在边集中的编号
len++;
tree[len].now = x;
tree[len].next = head[y];
head[y] = len;//记录头节点在边集中的编号
len++;
}
void dfs(int root) {
vis[root] = 1;
for(int i = head[root]; i != -1; i = tree[i].next) {
int now = tree[i].now;//拿到孩子的节点编号
if(!vis[now]) {
dfs(now);//向下撸
sum[root] += sum[now];//加上孩子的点数
if(son[root] < sum[now])//记录下最大孩子的点数
son[root] = sum[now];
}
}
}
int main() {
freopen("data.in", "r", stdin);
int T, n, x, y;
scanf("%d", &T);
while(T--) {
scanf("%d", &n);
len = 0;
memset(tree, 0, sizeof(tree));
memset(head, -1, sizeof(head));
for(int i = 1; i <= n-1; i++) {
scanf("%d%d", &x, &y);
add(x, y);//建树
}
memset(son, 0, sizeof(son));
memset(vis, 0, sizeof(vis));
for(int i = 1; i <= n; ++i)
sum[i] = 1;//自身初值为1
dfs(1);
int pos = 1;
int ans = son[1];
for(int i = 2; i < n; i++) {
if(ans > max(sum[1]-sum[i], son[i])) {//去掉i点,i向上 i向下
ans = max(sum[1]-sum[i], son[i]);
pos = i;
}
}
printf("%d %d\n", pos, ans);
}
return 0;
}
POJ 1655 Balancing Act(树形DP)
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转载自blog.csdn.net/ccshijtgc/article/details/81065161
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