Day 37 C. Kefa and Park

最新推荐文章于 2022-10-31 19:41:48 发布

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最新推荐文章于 2022-10-31 19:41:48 发布 · 234 阅读

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Kefa打算用他的第一份大薪水去餐厅庆祝。他住在一个由n个顶点组成的根树公园里，树的根节点是1，也是Kefa的家。公园里有些地方有猫，Kefa已经知道了哪些顶点有猫。他想选择一家餐厅，但如果从餐厅到他家的路径上连续超过m个有猫的顶点，他就会感到害怕。任务是帮助Kefa计算他可以去的餐厅数量。

Problem
Kefa decided to celebrate his first big salary by going to the restaurant.

He lives by an unusual park. The park is a rooted tree consisting of n vertices with the root at vertex 1. Vertex 1 also contains Kefa’s house. Unfortunaely for our hero, the park also contains cats. Kefa has already found out what are the vertices with cats in them.

The leaf vertices of the park contain restaurants. Kefa wants to choose a restaurant where he will go, but unfortunately he is very afraid of cats, so there is no way he will go to the restaurant if the path from the restaurant to his house contains more than m consecutive vertices with cats.

Your task is to help Kefa count the number of restaurants where he can go.

Input
The first line contains two integers, n and m (2 ≤ n ≤ 10^5, 1 ≤ m ≤ n) — the number of vertices of the tree and the maximum number of consecutive vertices with cats that is still ok for Kefa.

The second line contains n integers a1, a2, …, an, where each ai either equals to 0 (then vertex i has no cat), or equals to 1 (then vertex i has a cat).

Next n - 1 lines contains the edges of the tree in the format “xi yi” (without the quotes) (1 ≤ xi, yi ≤ n, xi ≠ yi), where xi and yi are the vertices of the tree, connected by an edge.

It is guaranteed that the given set of edges specifies a tree.

Output
A single integer — the number of distinct leaves of a tree the path to which from Kefa’s home contains at most m consecutive vertices with cats.

Examples
input
4 1
1 1 0 0
1 2
1 3
1 4
output
2

input
7 1
1 0 1 1 0 0 0
1 2
1 3
2 4
2 5
3 6
3 7
output
2

#include<iostream>
#include<algorithm>
#include<string.h>
#inc

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