AOC2022_Day21

op_mapping = {}
parts_mapping = {}

def operation(parts):
    if len(parts) == 2:
        return int(parts[1])
    else:
        f = op_mapping[parts[1]](parts_mapping[parts[1]])
        s = op_mapping[parts[3]](parts_mapping[parts[3]])
        if parts[2] == '+': return f + s
        elif parts[2] == '-': return f - s
        elif parts[2] == '*': return f * s
        else: return f / s

def backprop(result, node):
    parts = parts_mapping[node]
    if len(parts) == 2:
        if node == 'humn': return [result]
        else: return []
    else:
        f = op_mapping[parts[1]](parts_mapping[parts[1]])
        s = op_mapping[parts[3]](parts_mapping[parts[3]])
        if parts[2] == '+': return backprop(result - s, parts[1]) or backprop(result - f, parts[3])
        elif parts[2] == '-': return backprop(result + s, parts[1]) or backprop(f - result, parts[3])
        elif parts[2] == '*': return backprop(result / s, parts[1]) or backprop(result / f, parts[3])
        else: return backprop(result * s, parts[1]) or backprop(f/result, parts[3])

for i in range(len(input_lines)):
    line = input_lines[i]
    parts = line.split(' ')
    monkey = parts[0][:-1]
    op_mapping[monkey] = operation
    parts_mapping[monkey] = parts

def root_op(parts):
    f = op_mapping[parts[1]](parts_mapping[parts[1]])
    s = op_mapping[parts[3]](parts_mapping[parts[3]])
    return (backprop(f, parts[3]) or backprop(s, parts[1]))[0]

# Uncomment the following line to run part 2
# op_mapping['root'] = root_op
op_mapping['root'](parts_mapping['root'])