insulation.py

import numpy as np

# Use recursion to check insulation
def insulate(space, pos):
    # pos already discovered, skip
    if space[pos] == 2:
        pass
    # pos is on boundary
    if pos[0] <= 0 or pos[0] >= space.shape[0]-1 \
        or pos[1] <= 0 or pos[1] >= space.shape[1]-1 \
            or pos[2] <= 0 or pos[2] >= space.shape[2]-1:
        # if pos is 0 (air), implies air path to boundary, hence not insulated
        if space[pos] == 0:
            return 1
        # if pos is 1 (insulation), implies no air path to boundary, hence insulated
        else:
            return 0
    # pos not discovered, mark as discovered
    space[pos] = 2
    # check pos neighbors
    pos1 = pos[0], pos[1], pos[2] + 1
    pos2 = pos[0], pos[1], pos[2] - 1
    pos3 = pos[0], pos[1] + 1, pos[2]
    pos4 = pos[0], pos[1] - 1, pos[2]
    pos5 = pos[0] + 1, pos[1], pos[2]
    pos6 = pos[0] - 1, pos[1], pos[2]
    # if neighbor is 0 (air), recurse
    result = 0
    if space[pos1] == 0:
        result += insulate(space, pos1)
    if space[pos2] == 0:
        result += insulate(space, pos2)
    if space[pos3] == 0:
        result += insulate(space, pos3)
    if space[pos4] == 0:
        result += insulate(space, pos4)
    if space[pos5] == 0:
        result += insulate(space, pos5)
    if space[pos6] == 0:
        result += insulate(space, pos6)
    return result
    

def test(space, start=(4, 4, 4)):
    space[start] = 0 # center
    if insulate(space, (4, 4, 4)) == 0:
        print("Insulated")
    else:
        print("Not insulated")


if __name__ == "__main__":
    # examples
    space = np.zeros((10, 10, 10))
    space[0, :, :] = 1
    space[9, :, :] = 1
    space[:, 0, :] = 1
    space[:, 9, :] = 1
    space[:, :, 0] = 1
    space[:, :, 9] = 1
    test(space)

    space = np.zeros((10, 10, 10))
    space[1, :, :] = 1
    space[8, :, :] = 1
    space[:, 1, :] = 1
    space[:, 8, :] = 1
    space[:, :, 1] = 1
    space[:, :, 8] = 1
    test(space)
    
    space = np.zeros((10, 10, 10))
    space[2, :, :] = 1
    space[7, :, :] = 1
    space[:, 2, :] = 1
    space[:, 7, :] = 1
    space[:, :, 2] = 1
    space[:, :, 7] = 1
    test(space)

    space = np.zeros((10, 10, 10))
    space[3, :, :] = 1
    space[6, :, :] = 1
    space[:, 3, :] = 1
    space[:, 6, :] = 1
    space[:, :, 3] = 1
    space[:, :, 6] = 1
    test(space)

    space = np.zeros((10, 10, 10))
    space[4, :, :] = 1
    space[5, :, :] = 1
    space[:, 4, :] = 1
    space[:, 5, :] = 1
    space[:, :, 4] = 1
    space[:, :, 5] = 1
    test(space)

    # non-examples
    space = np.zeros((10, 10, 10))
    space[0, :, :] = 1
    space[9, :, :] = 1
    space[:, 0, :] = 1
    space[:, 9, :] = 1
    space[:, :, 0] = 1
    space[:, :, 9] = 1
    space[0, 4, 4] = 0 # hole on boundary
    test(space)

    space = np.zeros((10, 10, 10))
    space[0, :, :] = 1
    space[9, :, :] = 1
    space[:, 0, :] = 1
    space[:, 9, :] = 1
    space[:, :, 0] = 1
    # space[:, :, 9] = 1 # no roof
    test(space)

    space = np.zeros((10, 10, 10))
    space[0, :, :] = 1
    space[9, :, :] = 1
    space[:, 0, :] = 1
    # space[:, 9, :] = 1 # no wall
    space[:, :, 0] = 1
    space[:, :, 9] = 1 
    test(space)

    space = np.zeros((10, 10, 10))
    # nothing
    test(space)