class Solution:
    def numIslands(self, grid: List[List[str]]) -> int:

        from collections import deque

        def bfs(r, c):

            q = deque()
            visited.add((r, c))
            q.append((r, c))

            while q:
                row, col = q.popleft()
                directions = [[1, 0], [-1, 0], [0, 1], [0, -1]]

                for dr, dc in directions:
                    r, c = row + dr, col + dc
                    # error was here : r, c = row + dr, row + dc
                    if (r) in range(rows) and (c) in range(cols) and grid[r][c] == '1' and (r ,c) not in visited:
                        q.append((r , c ))
                        visited.add((r, c ))

        count = 0
        visited = set()
        rows = len(grid)
        cols = len(grid[0])

        for r in range(len(grid)):
            for c in range(len(grid[0])):
                if grid[r][c] == "1" and (r,c) not in visited:
                    bfs(r, c)
                    count = count + 1

        return count