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Improved Day 8 Part 2

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8.2-better 8.2b
Ishan Jain 1 year ago
parent 3a8ea28480
commit fdb93b534f
1 changed files with 62 additions and 193 deletions
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255
src/main.rs
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@ -1,6 +1,4 @@
#![feature(test)]
use std::collections::HashMap;
extern crate test;
const INPUTS: [&'static str; 2] = [
@ -12,215 +10,86 @@ const fn map_to_segment(c: char) -> u8 {
1 << (c as u8 - b'a')
}
fn parse_digits(ip: &str) -> Vec<u8> {
let mut out = Vec::with_capacity(ip.len());
for c in ip.chars() {
out.push(map_to_segment(c));
}
out.sort_unstable();
out
}
fn parse_input(input: &'static str) -> Vec<(Vec<Vec<u8>>, Vec<Vec<u8>>)> {
input
.lines()
.filter(|&x| !x.is_empty())
.map(|line| {
let (hints, displays) = line.split_once(" | ").unwrap();
let hints = hints
.split(' ')
.filter(|x| !x.is_empty())
.map(parse_digits)
.collect();
let digits = displays
.split(' ')
.filter(|x| !x.is_empty())
.map(parse_digits)
.collect();
(hints, digits)
})
.collect()
}
pub fn permute(mut nums: [u8; 7]) -> Vec<[u8; 7]> {
let mut ans = vec![];
let k = nums.len();
permute_helper(&mut nums, &mut ans, k);
ans
}
fn permute_helper(nums: &mut [u8; 7], permutations: &mut Vec<[u8; 7]>, k: usize) {
if k == 1 {
permutations.push(*nums);
} else {
for i in 0..k {
permute_helper(nums, permutations, k - 1);
if i < k - 1 {
if k % 2 == 0 {
nums.swap(i, k - 1);
} else {
nums.swap(0, k - 1);
fn parse_input(input: &'static str) -> impl Iterator<Item = (Vec<u8>, Vec<u8>)> {
input.lines().filter(|&x| !x.is_empty()).map(|line| {
let (hints, displays) = line.split_once(" | ").unwrap();
let hints = hints
.split(' ')
.filter(|x| !x.is_empty())
.map(|hint| {
let mut out = 0;
for c in hint.chars() {
out |= map_to_segment(c);
}
}
}
}
out
})
.collect();
let digits = displays
.split(' ')
.filter(|x| !x.is_empty())
.map(|hint| {
let mut out = 0;
for c in hint.chars() {
out |= map_to_segment(c);
}
out
})
.collect();
(hints, digits)
})
}
fn generate_charset(permutation: &[u8]) -> Vec<Vec<u8>> {
let mut answer = vec![vec![]; 10];
fn decode_hint(hints: Vec<u8>) -> [u8; 10] {
let mut out = [0; 10];
for digit in 0..=9 {
let mut out = vec![];
for &hint in hints.iter() {
match hint.count_ones() {
2 => out[1] = hint,
4 => out[4] = hint,
3 => out[7] = hint,
7 => out[8] = hint,
match digit {
0 => {
out.push(permutation[0]);
out.push(permutation[1]);
out.push(permutation[2]);
out.push(permutation[4]);
out.push(permutation[5]);
out.push(permutation[6]);
}
1 => {
out.push(permutation[2]);
out.push(permutation[5]);
}
2 => {
out.push(permutation[0]);
out.push(permutation[2]);
out.push(permutation[3]);
out.push(permutation[4]);
out.push(permutation[6]);
}
3 => {
out.push(permutation[0]);
out.push(permutation[2]);
out.push(permutation[3]);
out.push(permutation[5]);
out.push(permutation[6]);
}
4 => {
out.push(permutation[1]);
out.push(permutation[2]);
out.push(permutation[3]);
out.push(permutation[5]);
}
5 => {
out.push(permutation[0]);
out.push(permutation[1]);
out.push(permutation[3]);
out.push(permutation[5]);
out.push(permutation[6]);
}
6 => {
out.push(permutation[0]);
out.push(permutation[1]);
out.push(permutation[3]);
out.push(permutation[4]);
out.push(permutation[5]);
out.push(permutation[6]);
}
7 => {
out.push(permutation[0]);
out.push(permutation[2]);
out.push(permutation[5]);
}
8 => {
out.push(permutation[0]);
out.push(permutation[1]);
out.push(permutation[2]);
out.push(permutation[3]);
out.push(permutation[4]);
out.push(permutation[5]);
out.push(permutation[6]);
}
9 => {
out.push(permutation[0]);
out.push(permutation[1]);
out.push(permutation[2]);
out.push(permutation[3]);
out.push(permutation[5]);
out.push(permutation[6]);
}
_ => (),
}
answer[digit] = out;
}
answer
.into_iter()
.map(|mut set| {
set.sort_unstable();
set
})
.collect()
}
#[inline]
fn verify_perfect_overlap(d1: &[u8], d2: &[u8]) -> bool {
if d1.len() != d2.len() {
return false;
}
d1 == d2
}
fn find_best_fit(permutations: &[[u8; 7]], mut hints: Vec<Vec<u8>>) -> Option<Vec<Vec<u8>>> {
hints.sort_unstable_by(|a, b| a.len().cmp(&b.len()));
for permutation in permutations {
let charset = generate_charset(permutation);
let mut map = HashMap::new();
for (i, cset) in charset.iter().enumerate() {
for hint in hints.iter() {
if verify_perfect_overlap(&cset, &hint) {
if map.contains_key(&hint) {
continue;
} else {
map.insert(hint, i);
}
}
}
}
if map.len() == hints.len() {
return Some(charset);
for hint in hints {
let one_overlap = (hint & out[1]).count_ones();
let four_overlap = (hint & out[4]).count_ones();
match (hint.count_ones(), one_overlap, four_overlap) {
(5, 1, 2) => out[2] = hint,
(5, 2, 3) => out[3] = hint,
(5, 1, 3) => out[5] = hint,
(6, 1, 3) => out[6] = hint,
(6, 2, 4) => out[9] = hint,
(6, 2, 3) => out[0] = hint,
_ => (),
}
}
None
return out;
}
fn solution(input: Vec<(Vec<Vec<u8>>, Vec<Vec<u8>>)>) -> u64 {
// Generate all possible permutations of abcdefg
let permutations = permute([
0b0000001, 0b0000010, 0b0000100, 0b0001000, 0b0010000, 0b0100000, 0b1000000,
]);
fn solution(input: impl Iterator<Item = (Vec<u8>, Vec<u8>)>) -> i32 {
let mut answer = 0;
for (hints, digits) in input {
let best_fit = find_best_fit(&permutations, hints).unwrap();
let mut out_digit = String::new();
for digit in digits {
for (i, fit) in best_fit.iter().enumerate() {
if fit == &digit {
out_digit.push_str(&i.to_string());
let decoded_hints = decode_hint(hints);
let mut out = 0;
let offset = digits.len() as u32;
for (j, digit) in digits.into_iter().enumerate() {
for (i, &hint) in decoded_hints.iter().enumerate() {
if hint == digit {
out += i as i32 * 10i32.pow(offset - j as u32 - 1);
}
}
}
let parsed = u64::from_str_radix(&out_digit, 10).unwrap();
answer += parsed;
answer += out;
}
answer
@ -236,9 +105,9 @@ fn main() {
#[bench]
fn solution_bench(b: &mut test::Bencher) {
let input = parse_input(INPUTS[1]);
b.iter(|| {
let result = solution(input.clone());
let input = parse_input(INPUTS[1]);
let result = solution(input);
test::black_box(result);
})
}

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