18.py

raw = """
75
95 64
17 47 82
18 35 87 10
20 04 82 47 65
19 01 23 75 03 34
88 02 77 73 07 63 67
99 65 04 28 06 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 04 68 89 53 67 30 73 16 69 87 40 31
04 62 98 27 23 09 70 98 73 93 38 53 60 04 23"""
class Node:
    def __init__(self, val, row, col):
        self.val = val
        self.row = row
        self.col = col
        self.children = []
    def __hash__(self) -> int:
        return hash((self.val, self.row, self.col))
        

pyramid = []
for line in raw.strip().splitlines():
    line = line.strip()
    row = [Node(int(c), len(pyramid), i) for i, c in enumerate(line.split())]
    pyramid.append(row)
for row, nodes in enumerate(pyramid[:-1]):
    for col, node in enumerate(nodes):
        node.children = [pyramid[row+1][col], pyramid[row+1][col+1]]
assert not any(n.children for n in pyramid[-1])
assert pyramid[3][1].val == 35
assert pyramid[3][1].children[0].val == 4
assert pyramid[3][1].children[1].val == 82

from functools import lru_cache
@lru_cache(maxsize=None)
def max_path(node: Node) -> int:
    if not node.children:
        return node.val
    return max(node.val + max_path(child) for child in node.children)
print(max_path(pyramid[0][0]))