poj 1655 DP

#include<cstdio>#include<cstring>#define MAX(x,y) ((x)>(y)?(x):(y))struct node{int to,next;}e[41000];int cnt,head[21000],n;void add_edge(int from,int to){    e[cnt].to=to;e[cnt].next=head[from];head[from]=cnt++;}int dp[20010];int num[20010];void dfs(int u,int v){dp[u]=1;for(int i=head[u];i!=-1;i=e[i].next){int to=e[i].to;if(to==v)continue;dfs(to,u);dp[u]+=dp[to];num[u]=MAX(num[u],dp[to]);}}int main(){int T;scanf("%d",&T);while(T--){scanf("%d",&n);cnt=0;memset(head,-1,sizeof(head));for(int i=1;i<n;i++){int a,b;scanf("%d%d",&a,&b);add_edge(a,b);add_edge(b,a);}memset(num,0,sizeof(num)); dfs(1,-1); int res=0x3f3f3f3f,lo;for(int i=1;i<=n;i++){if(res>MAX(n-dp[i],num[i])){lo=i;res=MAX(n-dp[i],num[i]);}}printf("%d %d\n",lo,res);}}