[백준] 15900 나무 탈출 - Graph Theory / Java

• 문제 링크

15900번: 나무 탈출

 

• 풀이 과정

 

• 풀이 코드

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class Main {

    static int res = 0;
    static List<Integer>[] graph;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st;

        int n = Integer.parseInt(br.readLine());

        graph = new ArrayList[n + 1];
        for (int i = 1; i <= n; i++)
            graph[i] = new ArrayList<>();

        for (int i = 1; i < n; i++) {
            st = new StringTokenizer(br.readLine());
            int a = Integer.parseInt(st.nextToken());
            int b = Integer.parseInt(st.nextToken());

            graph[a].add(b);
            graph[b].add(a);
        }

        dfs(1, -1, 0);

        bw.write(res % 2 == 0 ? "No" : "Yes");
        bw.flush();
    }

    private static void dfs(int node, int parent, int depth) {
        if (graph[node].size() == 1 && graph[node].get(0) == parent) {
            res += depth;
            return;
        }

        for (int next : graph[node]) {
            if (next != parent)
                dfs(next, node, depth + 1);
        }
    }

}