Submission #1609537

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Source Code Expand

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

int n, x;
vector<int> h;
vector<vector<int>> G;
vector<bool> isVisited;
vector<int> dp;

void dfs(int s){
    int v = 0;
    for(int t : G[s]){
        if(isVisited[t]) continue;
        isVisited[t] = true;
        dfs(t);
        if(dp[t] > 0)
            v += dp[t] + 2;
        else if(h[t]){
            v += 2;
        }
    }
    dp[s] = v;
}

int main(){
    cin >> n >> x;
    x--;
    h.resize(n);
    G.resize(n);
    isVisited.resize(n, false);
    dp.resize(n, 0);
    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--;
        G[a].push_back(b);
        G[b].push_back(a);
    }
    isVisited[x] = true;
    dfs(x);
    cout << dp[x] << endl;
    return 0;
}

Submission Info

Judge Result