slide_down.py

# https://www.codewars.com/kata/551f23362ff852e2ab000037/train/python

def longest_slide_down(pyramid):
    pyrasum = []
    pyrasum.append([pyramid[0][0]])
    for lvl in range(len(pyramid)-1):
        tmp = [0]*len(pyramid[lvl+1])
        for i in range(len(pyramid[lvl+1])):
            v1 = (pyrasum[lvl][i - 1] if i > 0 else 0) + pyramid[lvl + 1][i]
            v2 = (pyrasum[lvl][i] if i < len(pyrasum[lvl]) else 0) + pyramid[lvl + 1][i]
            tmp[i] = max(v1,v2)
        pyrasum.append(tmp)
    return max(pyrasum[-1])

import codewars_test as test

@test.describe('longest_slide_down')
def test_longest_slide_down():
    @test.it('should work for small pyramids')
    def small_pyramids():
        test.assert_equals(longest_slide_down([[3], [7, 4], [2, 4, 6], [8, 5, 9, 3]]), 23)

    @test.it('should work for medium pyramids')
    def medium_pyramids():
        test.assert_equals(longest_slide_down([
            [75],
            [95, 64],
            [17, 47, 82],
            [18, 35, 87, 10],
            [20,  4, 82, 47, 65],
            [19,  1, 23, 75,  3, 34],
            [88,  2, 77, 73,  7, 63, 67],
            [99, 65,  4, 28,  6, 16, 70, 92],
            [41, 41, 26, 56, 83, 40, 80, 70, 33],
            [41, 48, 72, 33, 47, 32, 37, 16, 94, 29],
            [53, 71, 44, 65, 25, 43, 91, 52, 97, 51, 14],
            [70, 11, 33, 28, 77, 73, 17, 78, 39, 68, 17, 57],
            [91, 71, 52, 38, 17, 14, 91, 43, 58, 50, 27, 29, 48],
            [63, 66,  4, 68, 89, 53, 67, 30, 73, 16, 69, 87, 40, 31],
            [ 4, 62, 98, 27, 23,  9, 70, 98, 73, 93, 38, 53, 60,  4, 23],
            ]), 1074)