class Solution(object):
    def numIslands(self, grid):
        """
        :type grid: List[List[str]]
        :rtype: int
        """


        self.res = 0
        if not grid :
            return self.res

        self.drection = [[-1,0],[0,1],[1,0],[0,-1]]

        self.m = len(grid)

        self.n = len(grid[0])

        self.visit = [[False for i in range(self.n)] for i in range(self.m)]

        for x in range(self.m):
            for y in range(self.n):
                    if grid[x][y] == "1" and self.visit[x][y] == False:

                        self.res += 1
                        self.dfs(grid,x,y)

        return self.res

    def inArea(self,x,y):
        return x >= 0 and x < self.m and y >= 0 and y < self.n

    def dfs(self,grid,x,y):

        self.visit[x][y] = True

        for item in self.drection:
            newX = x + item[0]
            newY = y + item[1]

            if self.inArea(newX,newY) and self.visit[newX][newY] == False and grid[newX][newY] == "1":
                self.dfs(grid,newX,newY)

        return