C++ :

#include <iostream>
#include <vector>
using namespace std;

const int N = 1e3 + 5;

int n, k, maxn, col[N];
vector<int> g[N];

void dfs(int u, int fa, int cnt1, int cnt2) {
	if(cnt2 > k) return;//比k大了 
	maxn = max(maxn, cnt1);
	for(int i = 0; i < g[u].size(); i++) {
		int v = g[u][i];
		if(v != fa) {
			if(col[v] == 1) dfs(v, u, cnt1 + 1, cnt2 + 1);
			else dfs(v, u, cnt1 + 1, cnt2);
		}
	} 
}

int main() {
	cin >> n >> k;
	for(int i = 1; i <= n; i++) cin >> col[i];
	for(int i = 1; i < n; i++) {
		int u, v;
		cin >> u >> v;
		g[u].push_back(v);
		g[v].push_back(u);
	}
	for(int i = 1; i <= n; i++) {//暴力遍历 
		if(col[i] == 1) dfs(i, 0, 1, 1);
		else dfs(i, 0, 1, 0);
	}
	cout << maxn << endl;
	return 0;
}