백준 24481 java : 그래프, DFS

재귀 말고 스택을 사용하니까 꺼내는 순서 때문에 풀이가 잘 안된다. 게다가 지금 풀이도 메모리와 시간 소모가 너무 크다.

import java.util.Scanner;
import java.util.*;

public class bj24481 {
    static Scanner sc = new Scanner(System.in);
    static int N, M, R;
    static ArrayList<Integer>[] graph;

    public static void main(String[] args) {
        inputData();
        findAnswer();

        sc.close();
    }

    public static void inputData() {
        int i, u, v;

        N = sc.nextInt();
        M = sc.nextInt();
        R = sc.nextInt();
        graph = new ArrayList[N + 1];

        for(i = 1; i <= N; i++) {
            graph[i] = new ArrayList<>();
        }
        //무방향 그래프
        for(i = 0; i < M; i++){
            u = sc.nextInt();
            v = sc.nextInt();
            graph[u].add(v);
            graph[v].add(u);
        }

        for(i = 1; i <= N; i++) {
            Collections.sort(graph[i], Comparator.reverseOrder());
        }
    }

    public static void findAnswer() {
        Stack<Integer> stack = new Stack<>();
        boolean []visited = new boolean[N + 1];
        int [] depth = new int[N + 1];
        Arrays.fill(depth, -1);
        int current, i;

        depth[R] = 0;
        visited[R] = true;
        stack.push(R);
        while(!stack.isEmpty()){
            current = stack.pop();
            System.out.println("current : " + current + ", " + depth[current]);
            visited[current] = true;

            for(i = 1; i <= N; i++){
                System.out.print(depth[i] + " ");
            }
            System.out.println();

            for (int next : graph[current]) {
                if (!visited[next]) {
                    depth[next] = depth[current] + 1;
                    System.out.println("next : " + next + ", " + depth[next]);
                    stack.push(next);
                }
            }
        }

        for(i = 1; i <= N; i++){
            System.out.println(depth[i]);
        }
    }
}