릿코드200 - 섬의 수

class Solution:
    def numIslands(self, grid: List[List[str]]) -> int:
        ans = 0
        m = len(grid)
        n = len(grid[0])
        for i in range(m) : 
            for j in range(n) : 
                if grid[i][j] == "1" : 
                    ans += 1
                    self.check(grid, i, j)
        return ans
    
    def check(self, grid, i, j) : 
        dir = [
            [1, 0],
            [0, 1],
            [-1, 0],
            [0, -1]
        ]
        stack = [[i,j]]
        while stack : 
            i, j = stack.pop()
            grid[i][j] = 0
            for direction in dir : 
                X, Y = direction
                nextX, nextY = X + j, Y + i
                if nextX >= 0 and nextX < len(grid[0]) and nextY >= 0 and nextY < len(grid) and grid[nextY][nextX] == '1' :
                    stack.append([nextY, nextX])

대표적인 bfs, dfs 기본문제인 것 같다.