#include <cstdio>
#include <queue>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <set>
using namespace std;
const int maxv = 20011,inf = 1<<30;
bool vis[maxv]={false};
vector<int>G[maxv];
int n,father[maxv],maxD=-1;
set<int>ans;
void init()
{
for(int i = 1;i<=n;i++)
father[i] = i;
}
int findFather(int x)
{
int a = x;
while(x!=father[x])
x=father[x];
while(a!=father[a])
{
int z = a;
father[a] = x;
a = father[z];
}
return x;
}
void Union(int a,int b)
{
int faA = findFather(a);
int faB = findFather(b);
if(faA != faB)
father[faA] = faB;
}
void Dfs(int x,int d,int pre)
{
// vis[x] = true;
if(d>maxD)
{
maxD=d;
ans.clear();
ans.insert(x);
}
else if(d == maxD)
ans.insert(x);
for(int i = 0;i<G[x].size();i++)
{
int t = G[x][i];
if(t == pre) continue;
Dfs(t,d+1,x);
}
}
int main()
{
// freopen("1.txt","r",stdin);
scanf("%d",&n);
for(int i = 1;i<n;i++)
{
int id1,id2;
scanf("%d%d",&id1,&id2);
G[id1].push_back(id2);
G[id2].push_back(id1);
}
init();
for(int i = 1;i<=n;i++)
{
for(int j = 0;j<G[i].size();j++)
{
int u = i,v = G[i][j];
if(findFather(u) != findFather(v))
Union(u,v);
}
}
set<int>com;
for(int i = 1;i<=n;i++)
{
int temp = findFather(i);
com.insert(temp);
}
if(com.size() > 1)
printf("Error: %d components\n",com.size());
else
{
Dfs(1,1,-1);
// for(set<int>::iterator it= ans.begin();it!=ans.end();it++)
// {
// printf("%d",*it);
// }
set<int>temp = ans;
Dfs(*ans.begin(),1,-1);
for(set<int>::iterator it= temp.begin();it!=temp.end();it++)
{
ans.insert(*it);
}
for(set<int>::iterator it= ans.begin();it!=ans.end();it++)
{
printf("%d\n",*it);
}
}
return 0;
}
1021 Deepest Root (25 分)(太难了******)
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转载自blog.csdn.net/qq_15556537/article/details/101073687
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