Solution for number of islands problem on leetcode: https://leetcode.com/problems/number-of-islands/

islands.py

class Solution(object):
    def numIslands(self, grid):
        if (not grid): 
            return 0 
        
        rowLen = len(grid)
        columnLen = len(grid[0])
        
        islandCount = 0
        
        for row in range(rowLen): 
            for column in range(columnLen): 
                if (grid[row][column] == '1'): 
                    islandCount+=1
                    self.bfs(grid, row, column)

        return islandCount

    def bfs(self, grid, row, column): 
        queue = collections.deque()
        queue.append([row,column])
        
        while (queue): 
            x,y = queue.popleft()

            adjacents = [[x+1, y], [x-1, y], [x,y+1], [x,y-1]]

            for adjacent in adjacents:
                if (adjacent[0] > -1 and adjacent[0] < len(grid) and adjacent[1] > -1 and adjacent[1] < len(grid[0])):
                    if grid[adjacent[0]][adjacent[1]] == "1":  
                        grid[adjacent[0]][adjacent[1]] = "0"
                        queue.append([adjacent[0],adjacent[1]])