[leetCode/JS] 1926. Nearest Exit from Entrance in Maz

문제 설명

You are given an m x n matrix maze (0-indexed) with empty cells (represented as '.') and walls (represented as '+'). You are also given the entrance of the maze, where entrance = [entrancerow, entrancecol] denotes the row and column of the cell you are initially standing at.

In one step, you can move one cell up, down, left, or right. You cannot step into a cell with a wall, and you cannot step outside the maze. Your goal is to find the nearest exit from the entrance. An exit is defined as an empty cell that is at the border of the maze. The entrance does not count as an exit.

Return the number of steps in the shortest path from the entrance to the nearest exit, or -1 if no such path exists.

 

입출력 예

Example 1:

Input: maze = [["+","+",".","+"],[".",".",".","+"],["+","+","+","."]], entrance = [1,2]
Output: 1
Explanation: There are 3 exits in this maze at [1,0], [0,2], and [2,3].
Initially, you are at the entrance cell [1,2].

• You can reach [1,0] by moving 2 steps left.
• You can reach [0,2] by moving 1 step up.
• It is impossible to reach [2,3] from the entrance.
• Thus, the nearest exit is [0,2], which is 1 step away.

 

Example 2:

Input: maze = [["+","+","+"],[".",".","."],["+","+","+"]], entrance = [1,0]
Output: 2
Explanation: There is 1 exit in this maze at [1,2].
[1,0] does not count as an exit since it is the entrance cell.
Initially, you are at the entrance cell [1,0].

• You can reach [1,2] by moving 2 steps right.
• Thus, the nearest exit is [1,2], which is 2 steps away.

 

Example 3:

Input: maze = [[".","+"]], entrance = [0,0]
Output: -1
Explanation: There are no exits in this maze.

 

Constraints

• maze.length == m
• maze[i].length == n
• 1 <= m, n <= 100
• maze[i][j] is either '.' or '+'.
• entrance.length == 2
• 0 <= entrancerow < m
• 0 <= entrancecol < n
• entrance will always be an empty cell.

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내 솔루션

• 오우 쒯..
• 미로 찾기 문제다. 여러 조건이 있는데, 시작 지점은 출구가 아니다.
• 가로 세로 한칸씩 움직일 수 있고, 대각선으로는 움직일 수 없다.
• 출구가 없으면 -1을 돌려준다.
• BFS로 해결했고, maze[2]에다가 step level을 입력해주었다.
• 지나갈 때마다 '+'로 바꿔서 다시 돌아가지 못하게 visited 역할을 했다.

var permute = function(nums) {
var nearestExit = function(maze, entrance) {
  const queue = [[...entrance, 0]];
  const DIR = [[1,0], [-1,0], [0,1], [0,-1]]
  maze[entrance[0]][entrance[1]] = '+';

  while(queue.length) {
    const [curY, curX, level] = queue.shift();
    if((curY === 0 || curY === maze.length - 1 || curX === 0 || curX === maze[0].length - 1) && !(curY === entrance[0] && curX === entrance[1])){
      return level;
    }
    for(const [y, x] of DIR) {
      const posY = y + curY;
      const posX = x + curX;
      if(maze[posY]?.[posX] === '.'){
        maze[posY][posX] = '+';
        queue.push([posY, posX, level+1])
      }
    }
  }
  return -1;
};

감상평

• BFS로 하는 미로 찾기! 재미있었다.
• 원리를 알고 있어서 머릿속으로는 쉬운데 막상 코딩하면 시간이 걸린다.
• leetCode는 console.log()를 지원해서 중간 중간 디버깅을 할 수 있는데,
• 코딩테스트 플랫폼 중에는 console.log()가 막혀 있는 놈들이 있어서 눈으로 손으로 디버깅을 해야하는 점 때문에 console.log() 디버깅 습관을 고쳐야 하나 싶다.
• 근데 어떤 개발자가 log 안찍고 개발하냐? 뇌가 v8이냐? 왜 막아두는거요!
• 그리고 틀렸으면 어느 문제가 틀렸는지 안알려주는 플랫폼도 있다. 너넨 QA팀에서 그냥 안되던데요? 하더냐