class Solution:
    def numIslands(self, grid: List[List[str]]) -> int:
        searched_cell = set()
        def va(s):
            return int(s)
        # bfs
        ans = 0
        row = len(grid)
        column = len(grid[0])
        def add_node(que, idx, node):
            if len(que) <= idx:
                que.append(node)
            else:
                que[idx] = node
        def is_valid_node(node):
            i = node[0]
            j = node[1]
            return i >= 0 and j >= 0 and i < row and j <column
        flag = []
        for i, l in enumerate(grid):
            flag.append([])
            for j, lee in enumerate(l):
                flag[i].append(0)
        for i, l in enumerate(grid):
            for j, ele in enumerate(l):
                val = va(grid[i][j])
                if val == 0 : continue
                # if (i,j) in searched_cell: continue
                if flag[i][j] == 1: continue
                que = [(i, j)]
                idx = 0
                while idx >= 0:
                    node = que[idx]
                    # if node in searched_cell: continue
                    idx -= 1
                    if flag[node[0]][node[1]] == 1: continue
                    flag[node[0]][node[1]] = 1
                    if va(grid[node[0]][node[1]]) == 0: continue                    
                    up = (node[0] - 1, node[1])
                    down = (node[0] + 1, node[1])
                    left = (node[0], node[1] - 1)
                    right = (node[0], node[1] + 1)
                    if is_valid_node(up):
                        idx += 1
                        add_node(que, idx, up)
                    if is_valid_node(down):
                        idx += 1
                        add_node(que,idx, down)
                    if is_valid_node(left):
                        idx += 1
                        add_node(que, idx, left)
                    if is_valid_node(right):
                        idx += 1
                        add_node(que,idx, right)
                ans += 1
        return ans