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mod common;
use common::*;
fn solve_for_humn(name: &str, n1: i64, monkeys: &Vec<Monkey>) -> i64 {
if name == "humn" { return n1; }
let i = monkeys.iter().position(|m| m.name == name).unwrap();
if let MonkeyType::Op(op) = &monkeys[i].kind {
if let Some(n2) = result_or_unknown(&op.m1, &monkeys) {
// n1 = n2 [op] [unknown]
match op.op {
'+' => solve_for_humn(&op.m2, n1-n2, &monkeys),
'-' => solve_for_humn(&op.m2, n2-n1, &monkeys),
'*' => solve_for_humn(&op.m2, n1/n2, &monkeys),
'/' => solve_for_humn(&op.m2, n2/n1, &monkeys),
_ => panic!("invalid operator")
}
} else {
if let Some(n2) = result_or_unknown(&op.m2, &monkeys) {
// n1 = [unknown] [op] n2
match op.op {
'+' => solve_for_humn(&op.m1, n1-n2, &monkeys),
'-' => solve_for_humn(&op.m1, n1+n2, &monkeys),
'*' => solve_for_humn(&op.m1, n1/n2, &monkeys),
'/' => solve_for_humn(&op.m1, n1*n2, &monkeys),
_ => panic!("invalid operator")
}
} else { panic!("both sides undetermined"); }
}
} else { panic!("found number when trying to solve for humn"); }
}
fn result_or_unknown(name: &str, monkeys: &Vec<Monkey>) -> Option<i64> {
if name == "humn" { return None; }
let i = monkeys.iter().position(|m| m.name == name).unwrap();
match &monkeys[i].kind {
MonkeyType::Num(n) => Some(*n),
MonkeyType::Op(op) => {
let n1 = result_or_unknown(&op.m1, &monkeys)?;
let n2 = result_or_unknown(&op.m2, &monkeys)?;
Some(apply_op(n1, n2, op))
}
}
}
pub fn solve(monkeys: &Vec<Monkey>) -> i64 {
let i = monkeys.iter().position(|m| m.name == "root").unwrap();
if let MonkeyType::Op(op) = &monkeys[i].kind {
if let Some(n) = result_or_unknown(&op.m1, &monkeys) {
return solve_for_humn(&op.m2, n, monkeys);
} else {
if let Some(n) = result_or_unknown(&op.m2, &monkeys) {
return solve_for_humn(&op.m1, n, &monkeys);
} else { panic!("humn not found"); }
}
} else { panic!("root monkey is of type number"); }
}
fn main() {
let monkeys = read_monkeys_from_stdin();
println!("{}", solve(&monkeys));
}
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