Poj 2378 Tree Cutting(树形dp)

#include <cstdio>
#include <cstring>
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int sum[10005];//以该节点为父节点的子树的节点数量
int n,cnt,head[10005];
vector<int> v;
struct node{
int to;
int next;
}edge[20010];
void Add(int x,int y){
cnt++;
edge[cnt].to=y;
edge[cnt].next=head[x];
head[x]=cnt;
}
void DP(int x,int fa){
int re=0;
sum[x]=1;
for(int i=head[x];i;i=edge[i].next){
if(edge[i].to==fa){
continue;
}
DP(edge[i].to,x);
sum[x]+=sum[edge[i].to];
re=max(re,sum[edge[i].to]);
}
re=max(re,n-sum[x]);
if(re<=n/2){
v.push_back(x);
}
}
int main(){
int x,y;
while(scanf("%d",&n)!=EOF){
cnt=0;
memset(head,0,sizeof(head));
v.clear();
for(int i=1;i<n;i++){
scanf("%d%d",&x,&y);
Add(x,y);
Add(y,x);
}
DP(1,0);
sort(v.begin(),v.end());
for(int i=0;i<v.size();i++){
printf("%d\n",v[i]);
}
}
return 0;
}