Function that builds an n-deep binomial tree and returns the sum of the last level (practice from the PyconThailand 2018 code war)

binomial_sum.py

def build_tree(depth=3):
        curr_level = [1, 1]
        tree=[[1], curr_level]
        for i in range(depth-2):
                next_level = []
                for i in range(len(curr_level)-1):
                        next_level.append(curr_level[i] + curr_level[i+1])
                next_level = [1, *next_level, 1]
                curr_level = list(next_level)
                tree.append(curr_level)

        return tree

def run(depth):
        tree = build_tree(depth)

        print('\nTree sums\n---\n')
        for line in tree:
                print(line)
                print(sum(line))

        print(f"\n\n{len(tree)}th line sum is: {sum(tree[-1])}")

run(15)

build_tree_alt.py

import sys

def build_tree(depth):
    tree = [[1]]
    for i in range(depth):
        print(tree[-1])
        current_line = [i[0] + i[1] for i in zip(tree[-1], tree[-1][1:])]
        tree.append([1, *current_line, 1])
    return tree

if __name__ == "__main__":
    build_tree(int(sys.argv[1]))