1 #include<cstdio>
 2 #include<cstdlib>
 3 #include<cstring>
 4 #include<vector>
 5 #include<algorithm>
 6 using namespace std;
 7 //本题无向图中默认是没有环的
 8 //先任选一点A从该点开始dfs，找出距离该店最远的点B
 9 //然后从B点dfs,找到距离B最远的所有点，这些点加上B点都是deepest root
10
11 //用邻接表存储图
12 struct GraphNode
13 {
14     vector<int> adja;
15 };
16
17 bool *visited;
18 GraphNode *graph;
19
20 //从某个节点开始深度优先遍历图，并求出相应的树的高度，而且保存离树根最远的节点
21 void dfs(int rootIndex, int level, int &height, vector<int> &farthestNode)
22 {
23     visited[rootIndex] = true;
24     if(height < level)
25     {
26         height = level;
27         farthestNode.clear();
28         farthestNode.push_back(rootIndex);
29     }
30     else if(height == level)
31         farthestNode.push_back(rootIndex);
32     for(int i = 0; i < graph[rootIndex].adja.size(); i++)
33     {
34         int son = graph[rootIndex].adja[i];
35         if(visited[son] == false)
36             dfs(son, level+1, height, farthestNode);
37     }
38 }
39 int main()
40 {
41     int N;
42     scanf("%d", &N);
43     if(N == 1){printf("1"); return 0;}
44     graph = new GraphNode[N+1];
45     visited = new bool[N+1];
46     for(int i = 1; i <= N-1; i++)
47     {
48         int a,b;
49         scanf("%d%d", &a, &b);
50         graph[a].adja.push_back(b);
51         graph[b].adja.push_back(a);
52     }
53     vector<int> farthestNode;
54     int height = 0, components = 0;
55     memset(visited, 0, sizeof(bool)*(N+1));
56     //通过dfs遍历整个图来计算图的连通分支，调用dfs的次数就是连通分支数目
57     for(int i = 1; i <= N; i++)
58         if(visited[i] == false)
59         {
60             visited[i] == true;
61             dfs(i, 0, height, farthestNode);
62             components++;
63         }
64     if(components > 1)
65         printf("Error: %d components",components);
66     else
67     {
68         int k = farthestNode[0];
69         farthestNode.clear();
70         height = 0;
71         memset(visited, 0, sizeof(bool)*(N+1));
72         dfs(k, 0, height, farthestNode);
73         farthestNode.push_back(k);
74         sort(farthestNode.begin(), farthestNode.end());
75         for(int i = 0; i < farthestNode.size(); i++)
76             printf("%d\n", farthestNode[i]);
77     }
78     return 0;
79 }