树的重心

来源：互联网发布：网络教育高校编辑：程序博客网时间：2024/04/29 05:44
#include <map>#include <set>#include <stack>#include <queue>#include <cmath>#include <ctime>#include <vector>#include <cstdio>#include <cctype>#include <cstring>#include <cstdlib>#include <iostream>#include <algorithm>using namespace std;#define INF 0x3f3f3f3f#define inf -0x3f3f3f3f#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1#define mem0(a) memset(a,0,sizeof(a))#define mem1(a) memset(a,-1,sizeof(a))#define mem(a, b) memset(a, b, sizeof(a))typedef long long ll;const int maxn=21000;vector<int>G[maxn];int vis[maxn];int son[maxn];int ans,arise;;int n;void init(int n){    for(int i=1;i<=n;i++)        G[i].clear();    mem0(vis);}void dfs(int s){    vis[s]=1;    son[s]=0;    int balance=0;    for(int i=0;i<G[s].size();i++){        int x=G[s][i];        if(vis[x])            continue;        dfs(x);        son[s]+=son[x]+1;        balance=max(balance,son[x]+1);    }    balance=max(balance,n-son[s]-1);    if(balance<arise||(balance==arise&&s<ans)){        arise=balance;        ans=s;    }}int main(){    int t;    scanf("%d",&t);    while(t--){        int x,y;        scanf("%d",&n);        init(n);        for(int i=0;i<n-1;i++){            scanf("%d%d",&x,&y);            G[x].push_back(y);            G[y].push_back(x);        }        ans=1,arise=INF;        dfs(1);        printf("%d %d\n",ans,arise);    }    return 0;}
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