好吧，洪水填充的想法是：
def floodfill(matrix, x, y):
#"hidden" stop clause - not reinvoking for "c" or "b", only for "a".
if matrix[x][y] == "a":
matrix[x][y] = "c"
#recursively invoke flood fill on all surrounding cells:
if x > 0:
floodfill(matrix,x-1,y)
if x < len(matrix[y]) - 1:
floodfill(matrix,x+1,y)
if y > 0:
floodfill(matrix,x,y-1)
if y < len(matrix) - 1:
floodfill(matrix,x,y+1)
602392714
清零编程群