Advent of code 2022 - Day 21 solution - Python3

21.py

# time python 21.py
# python 21.py  0.48s user 0.12s system 79% cpu 0.748 total
#
#
import re
from collections import defaultdict
from sympy import solve

INPUT = '21.input'
memonkey = 'humn'
class Monkey:
    def __init__(self, line):
        onenum1 = re.match(r'(.*): (.+) (.) (.+)', line)
        onenum2 = re.match(r'(.*): (\d+)', line)
        self.dep = set()
        if onenum1:
            self.name = onenum1.group(1)
            self.expr = onenum1.group(2) + onenum1.group(3) + onenum1.group(4)
            self.dep.add(onenum1.group(2))
            self.dep.add(onenum1.group(4))
        elif onenum2:
            self.name = onenum2.group(1)
            self.expr = int(onenum2.group(2))
        else:
            print("ERROR", line)
    
    def fill(self, depname, depval):
        if depname in self.dep:
            self.dep.remove(depname)
            self.expr = self.expr.replace(depname, str(depval))
            if len(self.dep) == 0:
                self.expr = eval(self.expr)
                return self.expr
        return None
    
    def fill2(self, depname, depval):
        if depname in self.dep:
            self.dep.remove(depname)
            self.expr = self.expr.replace(depname, str(depval))
            if len(self.dep) == 0 and memonkey not in self.expr:
                self.expr = eval(self.expr)
                return self.expr
        return None
    
    def __str__(self):
        return f'{self.name}: {self.expr}'

    def __repr__(self):
        return self.__str__()


def main(lines):
    monkeys = {}
    dep = defaultdict(set)
    root = None
    for line in lines:
        line = line.strip()
        m = Monkey(line)
        monkeys[m.name] = m
        if m.name == 'root':
            root = m
        for d in m.dep:
            dep[d].add(m.name)
    while len(root.dep) > 0:
        mkeys = list(monkeys.keys())
        # print(mkeys)
        for mname in mkeys:
            m = monkeys[mname]
            # print(mname, m.dep, m.expr)
            if len(m.dep) == 0:
                for dependant in dep[mname]:
                    monkeys[dependant].fill(mname, m.expr)
                del dep[mname]
                del monkeys[mname]
    print(int(root.expr))

def main2(lines):
    memonkey = 'humn'
    monkeys = {}
    dep = defaultdict(set)
    root = None
    for line in lines:
        line = line.strip()
        m = Monkey(line)
        monkeys[m.name] = m
        if m.name == memonkey:
            m.expr = memonkey
        elif m.name == 'root':
            root = m
            m.expr = m.expr.replace('+', '==')
            m.expr = m.expr.replace('*', '==')
            m.expr = m.expr.replace('-', '==')
            m.expr = m.expr.replace('/', '==')
        for d in m.dep:
            dep[d].add(m.name)

    while len(root.dep) > 0:
        mkeys = list(monkeys.keys())
        # print(mkeys)
        for mname in mkeys:
            m = monkeys[mname]
            # print(mname, m.dep, m.expr)
            if len(m.dep) == 0:
                for dependant in dep[mname]:
                    monkeys[dependant].fill2(mname, f'({m.expr})')
                del dep[mname]
                del monkeys[mname]
    # print(root.expr)
    tosolve = root.expr.replace(memonkey, 'x')
    tosolve = tosolve[1:-1]
    tosolve = tosolve.replace(')==(', '-')
    # print(tosolve)
    sol = solve(tosolve)
    print(int(sol[0]))

                
if __name__ == '__main__':
    with open(INPUT) as f:
        lines = f.readlines()
    print("PART-1")
    main(lines)
    print("PART-2")
    main2(lines)