Return the maximum height of a continuous sequence of true values in a 2D array, starting from the bottom

skyline_max_height.py

import numpy


def get_max_height(skyline:numpy.ndarray) -> int:
    '''Returns the maximum height of a continuous sequence
    of true values in a 2D array, starting from the bottom'''
    mask = True
    return sum(any(mask := row & mask) 
               for row in reversed(skyline.astype(bool)))


def picture(skyline:numpy.ndarray, SEP=' '):
    STONE = "\N{LARGE GREEN SQUARE}"  
    BIRD  = "\N{LARGE RED SQUARE}"
    SKY   = "\N{LARGE BLUE SQUARE}"  
    image, stones = [], True    # stones is also a mask to trace a continuous line of true values
    for row in reversed(skyline.astype(bool)):
        # stones = row AND mask
        # birds  = row XOR stones
        # mask   = stones
        birds = row ^ (stones := row & stones)
        image.append(SEP.join(
            STONE if is_stone else BIRD if is_bird else SKY
            for is_stone, is_bird in zip(stones, birds)))
    print(*reversed(image), sep='\n')

    
picture(skyline := numpy.array([
    [1, 1, 0, 0],
    [0, 0, 1, 1],
    [1, 1, 1, 0],
    [0, 1, 0, 1],
    [1, 1, 0, 1],
]))

print(f'{get_max_height(skyline) = }')

https://twitter.com/gusthema/status/1482340641178857473