C++ 代码
#include<bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10, M = N * 2;
int n;
int h[N], e[M], ne[M], idx=1;
int vis[N];//为使在进入子节点时不会回到父节点
int res = N;
//将b节点连接至a节点的链表首部
void add(int a, int b)
{
e[idx] = b, ne[idx] = h[a], h[a] = idx++;
}
//返回以u为根节点的书的节点数
int dfs(int u)
{
vis[u] = 1;
int size = 0, sum = 1;
//size:删掉某个节点之后,最大的连通子图节点数
//sum:以u为根的树的节点数(包括u)
for (int i = h[u]; i != -1; i = ne[i])
{
int j = e[i];
if (!vis[j])
{
int s = dfs(j);
size = max(size, s);
sum += s;
//s:以j为根的树的节点数(包括j)
}
}
size = max(size, n - sum);
res = min(res, size);
return sum;
}
int main()
{
cin >> n;
memset(h, -1, sizeof h);
for (int i = 1; i <= n - 1; i++)
{
int a, b; scanf("%d%d", &a, &b);
add(a, b); add(b, a);
}
dfs(1);
cout << res << endl;
}