LeetCode 200 - Number of Islands - 2022.12.29 solution

class Solution:
    def numIslands(self, grid: List[List[str]]) -> int:
        """ How to solve it: Iterate through the grid.  When you hit a land cell, if it
        is not in a 'found_land' set, increment a variable tracking the number of found
        islands and then run DFS to add all positions in this island to the found_land
        set.
        """
        found_land = set()
        number_of_islands = 0
        ROWS = len(grid)
        COLS = len(grid[0])

        def add_land_neighbors_to_found_land(r, c):
            adjustments = [
                [0, 1],
                [0, -1],
                [1, 0],
                [-1, 0],
            ]
            neighbors = [(r + a[0], c + a[1]) for a in adjustments]
            for neighbor in neighbors:
                nr = neighbor[0]
                nc = neighbor[1]
                if nr < 0 or nr > ROWS - 1 or \
                   nc < 0 or nc > COLS - 1:
                   continue
                if (nr, nc) in found_land:
                    continue
                cell_value = grid[nr][nc]
                if cell_value == '0':
                    continue
                else:
                    found_land.add((nr, nc))
                    add_land_neighbors_to_found_land(nr, nc)

        for r in range(ROWS):
            for c in range(COLS):
                if (r, c) not in found_land and grid[r][c] == '1':
                    number_of_islands += 1
                    found_land.add((r, c))
                    add_land_neighbors_to_found_land(r, c)
        return number_of_islands