백준 1697 숨바꼭질(Java)

https://www.acmicpc.net/problem/1697

1697번: 숨바꼭질

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Java 코드

 

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import java.util.Scanner;
import java.util.Queue;
import java.util.LinkedList;

public class Main {

  static int[] arr = new int[100001];
  
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);

    int n = sc.nextInt();
    int k = sc.nextInt();

    bfs(n, k);
    
    System.out.println(arr[k] - 1);
  }

  public static void bfs(int a, int b) {
    Queue<Integer> q = new LinkedList<>();
    arr[a] = 1;
    q.add(a);

    while(!q.isEmpty()) {
      int num = q.poll();
      if(num == b) break;

      if(num - 1 >= 0 && arr[num - 1] == 0) {
        q.add(num - 1);
        arr[num - 1] = arr[num] + 1;
      }

      if(num + 1 <= 100000 && arr[num + 1] == 0) {
        q.add(num + 1);
        arr[num + 1] =  arr[num] + 1;
      }

      if(num * 2 <= 100000 && arr[num * 2] == 0) {
        q.add(num * 2);
        arr[num * 2] =  arr[num] + 1;
      }
    }
  }
  
}