Submission #1453775

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Source Code Expand

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

vector<int> v[100];
int h[100];
int n, x;

int dfs(int pos, int par){
	if(pos != x && v[pos].size() == 1){
		return (h[pos] ? 0 : -1);
	}else{
		int ret = 0;
		vector<int> add;
		for(int u : v[pos]){
			if(u != par){
				add.push_back(dfs(u, pos));
			}
		}
		for(int i = 0; i < add.size(); ++i){
			if(add[i] >= 0) ret += add[i] + 1;
		}
		return (ret ? ret: -1);
	}
}

int main(){
	cin >> n >> x;
	--x;
	for(int i = 0; i < n; ++i) cin >> h[i];
	for(int i = 0; i < n -1; ++i){
		int a, b; cin >> a >> b;
		--a; --b;
		v[a].push_back(b);
		v[b].push_back(a);
	}
	if(n == 1){
		cout << 0 << endl;
	}else{
		cout << max(dfs(x, -1) * 2, 0) << endl;
	}
	return 0;
}

Submission Info

Judge Result