LeetCode 695 - Max Area of Island - 2022.12.26 solution

class Solution:
    def maxAreaOfIsland(self, grid: List[List[int]]) -> int:
        # How to solve it: iterate through the cells in the grid, if you find
        # a part of an island that we haven't handled before, run DFS to find
        # all adjacent cells that are part of the same island, adding them to
        # a set of found land.  Have a variable that keeps track of the
        # largest land mass found.
        ROWS = len(grid)
        COLS = len(grid[0])
        land_positions_found = set()
        max_land_area = 0

        def get_size_of_island(y, x):
            neighbor_adjustments = [
                [0, 1],
                [0, -1],
                [1, 0],
                [-1, 0],
            ]
            neighbors = [(y + adj[0], x + adj[1]) for adj in neighbor_adjustments]
            size_of_island = 1
            for neighbor in neighbors:
                if neighbor[0] < 0 or neighbor[0] > ROWS - 1 or \
                   neighbor[1] < 0 or neighbor[1] > COLS - 1 or \
                   neighbor in land_positions_found:
                   continue
                if grid[neighbor[0]][neighbor[1]] == 1:
                    land_positions_found.add((neighbor[0], neighbor[1]))
                    size_of_island += get_size_of_island(neighbor[0], neighbor[1])
            return size_of_island


        i = 0
        while i < ROWS:
            j = 0
            while j < COLS:
                if (i, j) not in land_positions_found and grid[i][j] == 1:
                    land_positions_found.add((i, j))
                    area_of_island = get_size_of_island(i, j)
                    max_land_area = max(area_of_island, max_land_area)
                j += 1
            i += 1
        return max_land_area