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aoc2021
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Added Day 3 Part 2

This commit is contained in:
Ishan Jain 2021-12-03 19:03:56 +05:30
parent 53583df5e9
commit 4d7deb7de3
1 changed files with 36 additions and 27 deletions
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63
src/main.rs
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@ -14,32 +14,42 @@ fn cmds(input: &'static str) -> Vec<u64> {
.collect()
}
fn solution<const MAX_LINE_LENGTH: usize>(levels: &[u64]) -> i64 {
let dominant_mask = count_bits::<MAX_LINE_LENGTH>(&levels, true);
fn solution<const MAX_LENGTH: usize>(levels: Vec<u64>) -> u64 {
let oxygen_gen_rating = filter_candidates::<MAX_LENGTH>(levels.clone(), true);
let co2_scrub_rating = filter_candidates::<MAX_LENGTH>(levels, false);
let mut gamma = 0;
for i in (0..MAX_LINE_LENGTH).rev() {
let v = dominant_mask & (1 << i);
gamma <<= 1;
if v > 0 {
gamma |= 1;
} else {
gamma |= 0
}
}
let epsilon = !gamma & ((1 << MAX_LINE_LENGTH as i64) - 1);
gamma * epsilon
oxygen_gen_rating * co2_scrub_rating
}
fn count_bits<const LINE_LENGTH: usize>(levels: &[u64], dominant: bool) -> u64 {
fn filter_candidates<const MAX_LENGTH: usize>(mut levels: Vec<u64>, dominant: bool) -> u64 {
let mut i = 0;
while levels.len() > 1 {
let count = count_bits::<MAX_LENGTH>(&levels, dominant);
let leading = count & (1 << (MAX_LENGTH - i - 1));
levels = levels
.into_iter()
.filter(|&x| {
let pos = x & (1 << (MAX_LENGTH - i - 1));
return pos == leading;
})
.collect();
i += 1;
}
levels[0]
}
fn count_bits<const MAX_LENGTH: usize>(levels: &[u64], dominant: bool) -> u64 {
let n = levels.len();
let mut count = [0; LINE_LENGTH];
let mut count = [0; MAX_LENGTH];
let mut mask = 0;
for &level in levels.iter() {
for i in 0..LINE_LENGTH {
let c = level & (1 << i);
for i in 0..MAX_LENGTH {
let c = level & (1 << (MAX_LENGTH - i - 1));
if c != 0 {
count[i as usize] += 1;
@ -47,10 +57,9 @@ fn count_bits<const LINE_LENGTH: usize>(levels: &[u64], dominant: bool) -> u64 {
}
}
let mut mask = 0;
for (i, c) in count.into_iter().enumerate() {
if c >= n - c {
mask |= 1 << i;
mask |= 1 << (MAX_LENGTH - i - 1);
}
}
@ -63,10 +72,10 @@ fn count_bits<const LINE_LENGTH: usize>(levels: &[u64], dominant: bool) -> u64 {
fn main() {
let moves = cmds(INPUTS[0]);
let count = solution::<5>(&moves);
let count = solution::<5>(moves);
println!("Result {}", count);
let moves = cmds(INPUTS[1]);
let count = solution::<12>(&moves);
let count = solution::<12>(moves);
println!("Result {}", count);
}
@ -74,13 +83,13 @@ fn main() {
fn solution_bench(b: &mut test::Bencher) {
let moves = cmds(INPUTS[1]);
b.iter(|| {
let v = solution::<12>(&moves);
let v = solution::<12>(moves.clone());
test::black_box(v);
})
}
#[test]
fn solution_test() {
assert_eq!(solution::<5>(&cmds(INPUTS[0])), 198);
assert_eq!(solution::<12>(&cmds(INPUTS[1])), 3687446);
assert_eq!(solution::<5>(cmds(INPUTS[0])), 230);
assert_eq!(solution::<12>(cmds(INPUTS[1])), 4406844);
}