763A - Timofey and a tree

最新推荐文章于 2022-04-06 17:05:37 发布

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最新推荐文章于 2022-04-06 17:05:37 发布

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原文链接：http://www.cnblogs.com/mj-liylho/p/6376203.html

本文介绍了一道关于树结构的数据结构题目，Timofey需要找到一个节点作为根，使得所有子树内的颜色都一致，不含混合颜色。文章提供了完整的算法实现思路及代码。

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Each New Year Timofey and his friends cut down a tree of n vertices and bring it home. After that they paint all the n its vertices, so that the i-th vertex gets color ci.

Now it's time for Timofey birthday, and his mother asked him to remove the tree. Timofey removes the tree in the following way: he takes some vertex in hands, while all the other vertices move down so that the tree becomes rooted at the chosen vertex. After that Timofey brings the tree to a trash can.

Timofey doesn't like it when many colors are mixing together. A subtree annoys him if there are vertices of different color in it. Timofey wants to find a vertex which he should take in hands so that there are no subtrees that annoy him. He doesn't consider the whole tree as a subtree since he can't see the color of the root vertex.

A subtree of some vertex is a subgraph containing that vertex and all its descendants.

Your task is to determine if there is a vertex, taking which in hands Timofey wouldn't be annoyed.

Input

The first line contains single integer n (2 ≤ n ≤ 105) — the number of vertices in the tree.

Each of the next n - 1 lines contains two integers u and v (1 ≤ u, v ≤ n, u ≠ v), denoting there is an edge between vertices u and v. It is guaranteed that the given graph is a tree.

The next line contains n integers c1, c2, ..., cn (1 ≤ ci ≤ 105), denoting the colors of the vertices.

Output

Print "NO" in a single line, if Timofey can't take the tree in such a way that it doesn't annoy him.

Otherwise print "YES" in the first line. In the second line print the index of the vertex which Timofey should take in hands. If there are multiple answers, print any of them.

Examples

input

output

YES
2

input

output

YES
2

input

output

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<algorithm>
 4 #include<cstring>
 5 #include<cmath>
 6 #include<queue>
 7 #define pi acos(-1.0)
 8 #include<vector>
 9 typedef  long long  ll;
10 const int N=1e5+5;
11 using namespace std;
12 int c[N],f[N];
13 struct Node {
14     int v1, v2;
15     Node(int x = -1, int y = -1){//这是一个函数，v1,v2初始化为x,y
16         v1=x;
17         v2=y;
18     }
19 };
20 vector<Node> e;
21 int main()
22 {
23     int n;
24     int s,t,cnt=0;
25     scanf("%d",&n);
26     memset(f,0,sizeof(f));
27     for(int i=0;i<n-1;i++){
28         scanf("%d%d",&s,&t);
29         e.push_back(Node(s-1,t-1));//存入边
30     }
31     for(int i=0;i<n;i++){
32         scanf("%d",&c[i]);//i个点的颜色
33     }
34     for(int i=0;i<n-1;i++){
35         Node& u=e[i];
36         if(c[u.v1]!=c[u.v2]){
37             cnt++;
38             f[u.v1]++;
39             f[u.v2]++;
40         }
41     }
42     for(int i=0;i<n;i++){
43         if(f[i]==cnt){
44             printf("YES\n");
45             printf("%d\n",i+1);
46             return 0;
47         }
48     }
49     printf("NO\n");
50     return 0;
51 }