백준 15681번 : 트리와 쿼리 - DFS , C++

https://www.acmicpc.net/problem/15681

15681번: 트리와 쿼리

 

#include <bits/stdc++.h>
using namespace std;
#define MX 100001

int N, R, Q, dp[MX];
vector<int> adj[MX];
bool vis[MX];

int DFS(int node){
    dp[node] = 1;

    for(int i=0; i<adj[node].size(); i++){
        if(dp[adj[node][i]]==0)
            dp[node] += DFS(adj[node][i]);
    }

    return dp[node];
}


int main() {
    ios::sync_with_stdio(0); cin.tie(0);

    cin >> N >> R >> Q;
    for(int i=0; i<N-1; i++){
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    DFS(R);

    for(int i=0; i<Q; i++){
        int num;
        cin >> num;
        cout << dp[num] << '\n';
    }

    return 0;
}