def numIslands(self, grid):
if not grid or not grid[0]: return 0
row, col = len(grid), len(grid[0])
self.visited = [[False for _ in range(col)] for _ in range(row)]
def floodfill(i, j):
if grid[i][j] == '1' and self.visited[i][j] == False:
self.visited[i][j] = True
if i > 0:
floodfill(i - 1, j)
if i < row - 1:
floodfill(i + 1, j)
if j > 0:
floodfill(i, j - 1)
if j < col - 1:
floodfill(i, j + 1)
res = 0
for i in range(row):
for j in range(col):
if grid[i][j] == '1' and self.visited[i][j] == False:
res += 1
floodfill(i, j)
return res