Submission #1873444

---

Source Code Expand

#include "bits/stdc++.h"
using namespace std;

#define FOR(i,a,b) for(int (i)=(a);i<(int)(b);i++)
#define rep(i,n) FOR(i,0,n)
#define mset(a,x) memset(a,x,sizeof(a))
#define FASTIO() cin.tie(0),ios::sync_with_stdio(0);

bool visited[114];
vector<vector<int>> G;
vector<int> h;
int n, x;
int ans = 0;

bool dfs(int v) {
    visited[v] = true;
    bool r = false;
    for (auto&& to : G[v]) {
        if (!visited[to] && dfs(to)) {
            r = true;
            ans += 2;
        }
    }
    return r |= h[v];
}


int main() {
    FASTIO();
    mset(visited, false);
    cin >> n >> x;
    x--;
    G.resize(n); h.resize(n);
    rep(i, n) cin >> h[i];
    rep(i, n - 1) {
        int a, b; cin >> a >> b;
        a--; b--;
        G[a].push_back(b); G[b].push_back(a);
    }

    auto b = dfs(x);
    cout << ans << endl;

    return 0;
}

Submission Info

Judge Result