gen_neighbors_4c.py

def get_neighbors_4C(self, pt):
    # put self.gird in your class private
    x,y = pt[0], pt[1]
    
    # x positive top down, Y to the right
    maxX = len(self.grid)
    maxY = len(self.grid[0])
    # define the neighbor pattern
    nc4 = '[[x-1,y], [x+1,y], [x,y-1], [x,y+1]]'
    # generate all possible points
    pts = eval(nc4)
    # then only select the valid ones 这种搞法会浪费内存，但是简单不容易错，适用于大多cases
    neighbors = []
    for pt in pts:
        x,y = pt[0], pt[1]
        if 0<=x<maxX and 0<=y<maxY:
            neighbors.append([x,y])

    return neighbors