2020/python/day18.py

import fileinput


def find_matching_parenthesis(line):
    depth = 1
    for i, c in enumerate(line[1:]):
        if c == "(":
            depth += 1
        if c == ")":
            depth -= 1
        if depth == 0:
            break
    return i


def solve(line):
    print("".join(line))
    if line[0].isdigit():
        if len(line) == 1:
            return int(line[0])

        if len(line) == 3:
            if line[1] == "+":
                return int(line[0]) + int(line[2])
            if line[1] == "*":
                return int(line[0]) * int(line[2])

        if line[1] == "+":
            if line[2] == "(":
                closing = find_matching_parenthesis(line[2:])
                inner = int(line[0]) + solve(line[3 : closing + 4])
                return solve([str(inner)] + line[closing + 5 :])
            else:
                v = solve(line[:3])
                return solve([str(v)] + line[3:])

        if line[1] == "*":
            return solve(line[:1]) * solve(line[2:])
        raise BaseException(f"HELP {repr(line)}")

    if line[0] == "(":
        closing = find_matching_parenthesis(line[1:])
        inner = str(solve(line[1 : closing +2]))
        return solve([inner] + line[closing +3 :])


summ = 0
for line in fileinput.input():
    line = line.replace(" ", "").strip()
    v = solve(list(line))
    print(line, v)
    summ += v
print(summ)