Submission #1604769

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Source Code Expand

#include <bits/stdc++.h>
  
using namespace std;
  
#define rep(i,n) REP(i,0,n)
#define REP(i,s,e) for(int i=(s); i<(int)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for(int i=(int)(s-1); i>=(int)(e); i--)
#define pb push_back
#define all(r) (r).begin(),(r).end()
#define rall(r) (r).rbegin(),(r).rend()
#define fi first
#define se second
  
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
 
const int INF = 1e9;
const ll MOD = 1e9 + 7;
double EPS = 1e-8;

const int MAX_N = 110;
vi es[MAX_N];
vector<int> h;

int dfs(int cur, int par) {
    int ret = 0;
    for(auto& to : es[cur]) {
        if(to == par) continue;
        ret += dfs(to, cur);
    }
    if(par == -1) return ret;
    if(ret != 0 || h[cur] == 1) ret += 2;
    return ret;
}


int main(){
#ifdef LOCAL_TEST
    freopen("in", "r", stdin);
    freopen("out", "w", stdout);
#endif
    int n, x;
    cin >> n >> x;
    x--;
    h.resize(n);
    rep(i, n) cin >> h[i];
    rep(i, n-1) {
        int a, b;
        cin >> a >> b;
        a--; b--;
        es[a].pb(b);
        es[b].pb(a);
    }
    cout << dfs(x, -1) << endl;
    return 0;
}

Submission Info

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