Submission #286735

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Source Code Expand

#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<vector>
#include<cmath>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<numeric>
#include<functional>
#include<complex>
#include<cassert>

using namespace std;
#define BET(a,b,c) ((a)<=(b)&&(b)<(c))
#define FOR(i,n) for(int i=0;i<(int)(n);i++)
#define SZ(x) (int)(x.size())
#define ALL(x) (x).begin(),(x).end()
#define MP make_pair
#define CLS(x,val) memset((x) , val , sizeof(x)) 
#define FOR_EACH(it,v) for(__typeof(v.begin()) it=v.begin(),it_end=v.end() ; it != it_end ; it++)
typedef long long ll_t;
typedef long double ld_t;
typedef vector<int> VI;
typedef vector<VI> VVI;

typedef complex<int> xy;

VVI adj;
int h[111];

pair<int,int> dfs(int pos, int pre){
    int val = 0;
    int starNum = 0;
    if(h[pos]) starNum = 1;
    for(auto next : adj[pos]){
        if(next == pre) continue;
        auto sub = dfs(next, pos);
        if(sub.second == 0) continue;
        val += sub.first + 2;
        starNum += sub.second;
    }
    return MP(val, starNum);
}

int main()
{
    int n,x;
    cin>>n>>x;
    FOR(i,n) cin>>h[i];
    adj.resize(n);
    FOR(i,n-1){
        int a,b;
        cin>>a>>b;
        a--; b--;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    cout<<dfs(x-1, -1).first<<endl;
    return 0;
}

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