poj2378树形dp

#pragma GCC optimize(2)
#include<vector>
#include<cstdio>
#include<algorithm>
using namespace std;
typedef long long ll;
const int maxn = 1e4+5;
int Case = 1, n;
vector<int>ve[maxn], res;
int in[maxn];
int dfs(int u, int pre) {
	int temp = 0, sum = 1;
	for(int i = 0; i < ve[u].size(); i++) {
		if(ve[u][i] == pre) continue;
		int t = dfs(ve[u][i], u);
		temp = max(temp, t);
		sum += t;
	}
	if(temp <= n/2 && n-sum<=n/2) res.push_back(u);
	return sum;
}
void solve() {
    scanf("%d", &n);
    for(int i = 1; i < n; i++) {
    	int u, v;scanf("%d%d", &u, &v);
    	ve[u].push_back(v);
    	ve[v].push_back(u);
    }
    dfs(1, -1);
    sort(res.begin(), res.end());
    if(!res.size())printf("NONE\n");
    else for(int i = 0; i < res.size(); i++) printf("%d\n", res[i]);
    return;
}

int main() {
    while(Case--) {
        solve();
    }
    return 0;
}