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use std::io;
fn main() -> io::Result<()> {
let eqns = io::stdin()
.lines()
.flatten()
.collect::<Vec<_>>()
.iter()
.map(|line| line.split_once(": ").unwrap())
.map(|(ans, nums)| {
(
ans.parse::<u64>().unwrap(),
nums.split_whitespace()
.map(|s| s.parse::<u64>().unwrap())
.collect::<Vec<_>>(),
)
})
.collect::<Vec<_>>();
let silver: u64 = eqns
.iter()
.filter(|(ans, nums)| calibration(ans, nums, false))
.map(|(ans, _)| ans)
.sum();
let gold: u64 = eqns
.iter()
.filter(|(ans, nums)| calibration(ans, nums, true))
.map(|(ans, _)| ans)
.sum();
println!("silver: {silver}");
println!("gold: {gold}");
return Ok(());
}
fn concat(x: &u64, y: &u64) -> u64 {
x * (10u64.pow(y.ilog10() + 1)) + y
}
fn calibration(want: &u64, nums: &[u64], gold: bool) -> bool {
match nums {
[] => unreachable!(),
[x] => want == x,
[x, y, xs @ ..] => {
if x > want {
return false;
}
calibration(want, &[&[x + y], xs].concat(), gold) ||
calibration(want, &[&[x * y], xs].concat(), gold) ||
(gold && calibration(want, &[&[concat(x, y)], xs].concat(), gold) )
}
}
}
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