Submission #1628224

---

Source Code Expand

#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;


vector<int> H;
vector<int> X;
vector< vector<int> > P;

int dfs( int v, int p ) {
    
    for ( int i = 0; i < P[v].size(); i++ ) {        
        if ( p != P[v][i] && dfs( P[v][i], v ) ) { X[v] = 1; }
    }
    if ( H[v] ) { X[v] = 1; }
    
    return X[v];
}


int main() {
    
    int n,x;
    cin >> n >> x;
    x--;
    
    H.resize(n);
    X.resize(n);
    P.resize(n);
    
    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--;
        P[a].push_back(b);
        P[b].push_back(a);
    }
    
    dfs( x, -1 );
    
    int count = 0;
    for ( int i = 0; i < n; i++ ) {
        if ( i != x && X[i] ) { count++; }
    }
    
    cout << count*2 << endl;
    
    return 0;
}

Submission Info

Judge Result