59 lines
1.5 KiB
Rust
59 lines
1.5 KiB
Rust
#![warn(clippy::pedantic)]
|
|
use std::io::{stdin, BufRead};
|
|
|
|
fn find_rating(num_bits: usize, mut range: &[usize], keep_most_common_bit: bool) -> usize {
|
|
for idx in (0..num_bits).rev() {
|
|
if range.len() == 1 {
|
|
break;
|
|
}
|
|
|
|
let nth_bit = |x| x >> idx & 1;
|
|
let partition_point = range.iter().position(|&n| nth_bit(n) == 1).unwrap();
|
|
let center_bit = nth_bit(range[range.len() / 2]);
|
|
|
|
let keep_first_half = if keep_most_common_bit {
|
|
center_bit == 0
|
|
} else {
|
|
center_bit == 1
|
|
};
|
|
|
|
if keep_first_half {
|
|
range = &range[..partition_point];
|
|
} else {
|
|
range = &range[partition_point..];
|
|
}
|
|
}
|
|
|
|
range[0]
|
|
}
|
|
|
|
fn main() {
|
|
let lines: Vec<_> = stdin().lock().lines().map(Result::unwrap).collect();
|
|
|
|
let num_bits = lines[0].len();
|
|
|
|
let gamma: usize = (0..num_bits)
|
|
.map(|i| {
|
|
lines
|
|
.iter()
|
|
.filter(|line| line.chars().nth(i).unwrap() == '1')
|
|
.count()
|
|
})
|
|
.map(|n| if n > lines.len() / 2 { 1 } else { 0 })
|
|
.reduce(|accum, bit| accum << 1 | bit)
|
|
.unwrap();
|
|
let sigma = !gamma & ((1 << num_bits) - 1);
|
|
|
|
println!("{}", gamma * sigma);
|
|
|
|
let mut numbers: Vec<_> = lines
|
|
.iter()
|
|
.map(|n| usize::from_str_radix(n, 2).unwrap())
|
|
.collect();
|
|
numbers.sort_unstable();
|
|
|
|
let oxygen = find_rating(num_bits, &numbers, true);
|
|
let co2 = find_rating(num_bits, &numbers, false);
|
|
println!("{}", oxygen * co2);
|
|
}
|