day 3 part 2

this is horrible, thank you
main
anna 2 years ago
parent 0d245f117b
commit af7f6179df
Signed by: fef
GPG Key ID: EC22E476DC2D3D84

@ -15,4 +15,8 @@ path = "src/day02/main.rs"
name = "day03p1"
path = "src/day03p1/main.rs"
[[bin]]
name = "day03p2"
path = "src/day03p2/main.rs"
[dependencies]

@ -0,0 +1,105 @@
use std::io;
// there is no real reason to make this a struct i think
struct SortedNums {
zero: Vec<u32>,
one: Vec<u32>,
}
impl SortedNums {
/// Sort all numbers in `v` by whether `bit` is a one or zero
fn sort(v: &Vec<u32>, bit: usize) -> SortedNums {
assert!(bit < 32);
let mut zero = Vec::new();
let mut one = Vec::new();
for num in v {
if (*num & (1 << bit)) != 0 {
one.push(*num);
} else {
zero.push(*num);
}
}
SortedNums {
zero,
one,
}
}
}
// i have a very strong suspicion this is in the standard library
enum Pick {
More,
Less
}
impl Pick {
// also this should probably use references but the borrow
// checker pissed me off way too hard for me to care
pub fn pick<T>(&self, more: T, less: T) -> T {
match self {
Pick::More => more,
Pick::Less => less,
}
}
}
fn do_single_sort(nums: &Vec<u32>, bit: usize, which: Pick) -> Vec<u32> {
let sn = SortedNums::sort(nums, bit);
if sn.one.len() < sn.zero.len() {
which.pick(sn.zero, sn.one)
} else {
which.pick(sn.one, sn.zero)
}
}
fn main() {
let stdin = io::stdin();
let mut num_bits = 0usize;
let mut oxy_nums = Vec::new();
let mut co2_nums = Vec::new();
// I don't really consider this part of the algorithm itself, it's just
// obtaining the initial data. You could further optimize this by doing
// the first sorting round directly in here, though.
loop {
let mut buf = String::new();
match stdin.read_line(&mut buf).unwrap() {
0 => break,
_ => {
let numstr = buf.trim();
if num_bits == 0 {
if numstr.len() > 32 {
panic!("Only up to 32 bits supported");
}
num_bits = numstr.len();
} else if numstr.len() != num_bits {
panic!("Inconsistent number of bits");
}
let input = u32::from_str_radix(numstr, 2).unwrap();
oxy_nums.push(input);
co2_nums.push(input);
}
}
}
// if you wanted to get really fancy you could put co2
// and oxygen into an array along with their Pick rule
for bit in (0..num_bits).rev() {
if oxy_nums.len() > 1 {
oxy_nums = do_single_sort(&oxy_nums, bit, Pick::More);
}
if co2_nums.len() > 1 {
co2_nums = do_single_sort(&co2_nums, bit, Pick::Less);
}
}
assert_eq!(oxy_nums.len(), 1);
assert_eq!(co2_nums.len(), 1);
println!("oxygen: {}", oxy_nums[0]);
println!("co2: {}", co2_nums[0]);
println!("answer: {}", oxy_nums[0] * co2_nums[0]);
}
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