99클럽 코테 스터디 10일차 TIL - 백준[18352]

문제 풀이

오늘의 문제 - 백준18352.특정 거리의 도시 찾기

나의 풀이

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());

        int n = Integer.parseInt(st.nextToken());
        int m = Integer.parseInt(st.nextToken());
        int k = Integer.parseInt(st.nextToken());
        int x = Integer.parseInt(st.nextToken());

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

        for (int i = 0; i < m; i++) {
            st = new StringTokenizer(br.readLine());
            int a = Integer.parseInt(st.nextToken());
            int b = Integer.parseInt(st.nextToken());
            graph[a].add(b);
        }

        int[] distance = new int[n + 1];
        Arrays.fill(distance, -1);
        distance[x] = 0;

        Queue<Integer> queue = new LinkedList<>();
        queue.add(x);

        while (!queue.isEmpty()) {
            int current = queue.poll();

            for (int next : graph[current]) {
                if (distance[next] == -1) {
                    distance[next] = distance[current] + 1;
                    queue.add(next);
                }
            }
        }

        boolean found = false;
        for (int i = 1; i <= n; i++) {
            if (distance[i] == k) {
                System.out.println(i);
                found = true;
            }
        }

        if (!found) {
            System.out.println(-1);
        }
    }
}