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Ian Liu
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use std::collections::LinkedList; | ||
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advent_of_code::solution!(9); | ||
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pub fn part_one(input: &str) -> Option<u64> { | ||
let sequence = convert_input_to_sequence(input); | ||
let compressed_sequence = compress_sequence(sequence); | ||
let check_sum = get_check_sum(compressed_sequence); | ||
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Some(check_sum) | ||
} | ||
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pub fn part_two(input: &str) -> Option<u64> { | ||
let sequence = convert_input_to_sequence(input); | ||
let compressed_sequence = compress_sequence2(sequence); | ||
let check_sum = get_check_sum(compressed_sequence); | ||
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Some(check_sum) | ||
} | ||
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fn convert_input_to_sequence(input: &str) -> Vec<i32> { | ||
let input = input.lines().next().unwrap(); | ||
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let mut sequence = vec![]; | ||
let mut is_file = true; | ||
let mut id = 0; | ||
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for num in input.chars() { | ||
let num = num.to_digit(10).unwrap() as usize; | ||
if is_file { | ||
sequence.extend(vec![id; num]); | ||
id += 1; | ||
} else { | ||
sequence.extend(vec![-1; num]); | ||
} | ||
is_file = !is_file; | ||
} | ||
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sequence | ||
} | ||
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fn compress_sequence(mut sequence: Vec<i32>) -> Vec<i32> { | ||
let mut right = sequence.iter().rposition(|&x| x != -1).unwrap(); | ||
for left in 0..sequence.len() { | ||
if left >= right { | ||
break; | ||
} | ||
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let num = sequence[left]; | ||
if num == -1 { | ||
sequence[left] = sequence[right]; | ||
sequence[right] = -1; | ||
right -= 1; | ||
while sequence[right] == -1 { | ||
right -= 1; | ||
} | ||
} | ||
} | ||
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sequence | ||
} | ||
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fn get_check_sum(sequence: Vec<i32>) -> u64 { | ||
sequence | ||
.iter() | ||
.enumerate() | ||
.map( | ||
|(i, &num)| { | ||
if num == -1 { | ||
0 | ||
} else { | ||
i as u64 * num as u64 | ||
} | ||
}, | ||
) | ||
.sum() | ||
} | ||
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fn get_sections(sequence: &Vec<i32>) -> (Vec<(usize, usize)>, Vec<(usize, usize)>) { | ||
let mut file_sections = vec![]; | ||
let mut free_sections = vec![]; | ||
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let mut i = 0; | ||
while i < sequence.len() { | ||
let section_type = sequence[i]; | ||
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let mut j = i; | ||
while j < sequence.len() && sequence[j] == section_type { | ||
j += 1; | ||
} | ||
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if section_type != -1 { | ||
file_sections.push((i, j - i)); | ||
} else { | ||
free_sections.push((i, j - i)); | ||
} | ||
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i = j; | ||
} | ||
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(file_sections, free_sections) | ||
} | ||
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fn compress_sequence2(mut sequence: Vec<i32>) -> Vec<i32> { | ||
let (mut file_sections, mut free_sections) = get_sections(&sequence); | ||
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while let Some((file_idx, file_len)) = file_sections.pop() { | ||
for item in free_sections.iter_mut() { | ||
if item.0 > file_idx { | ||
continue; | ||
} | ||
if item.1 >= file_len { | ||
for delta in 0..file_len { | ||
sequence[item.0 + delta] = sequence[file_idx]; | ||
} | ||
for delta in 0..file_len { | ||
sequence[file_idx + delta] = -1; | ||
} | ||
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*item = (item.0 + file_len, item.1 - file_len); | ||
break; | ||
} | ||
} | ||
} | ||
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sequence | ||
} | ||
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#[cfg(test)] | ||
mod tests { | ||
use super::*; | ||
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#[test] | ||
fn test_part_one() { | ||
let sequence = | ||
convert_input_to_sequence(&advent_of_code::template::read_file("examples", DAY)); | ||
assert_eq!( | ||
sequence, | ||
vec![ | ||
0, 0, -1, -1, -1, 1, 1, 1, -1, -1, -1, 2, -1, -1, -1, 3, 3, 3, -1, 4, 4, -1, 5, 5, | ||
5, 5, -1, 6, 6, 6, 6, -1, 7, 7, 7, -1, 8, 8, 8, 8, 9, 9 | ||
] | ||
); | ||
let compressed_sequence = compress_sequence(sequence); | ||
assert_eq!( | ||
compressed_sequence, | ||
vec![ | ||
0, 0, 9, 9, 8, 1, 1, 1, 8, 8, 8, 2, 7, 7, 7, 3, 3, 3, 6, 4, 4, 6, 5, 5, 5, 5, 6, 6, | ||
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 | ||
] | ||
); | ||
let check_sum = get_check_sum(compressed_sequence); | ||
assert_eq!(check_sum, 1928); | ||
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let result = part_one(&advent_of_code::template::read_file("examples", DAY)); | ||
assert_eq!(result, Some(1928)); | ||
} | ||
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#[test] | ||
fn test_part_two() { | ||
let sequence = | ||
convert_input_to_sequence(&advent_of_code::template::read_file("examples", DAY)); | ||
let (file_sections, free_sections) = get_sections(&sequence); | ||
assert_eq!( | ||
file_sections, | ||
vec![ | ||
(0, 2), | ||
(5, 3), | ||
(11, 1), | ||
(15, 3), | ||
(19, 2), | ||
(22, 4), | ||
(27, 4), | ||
(32, 3), | ||
(36, 4), | ||
(40, 2) | ||
] | ||
); | ||
assert_eq!( | ||
free_sections, | ||
vec![ | ||
(2, 3,), | ||
(8, 3,), | ||
(12, 3,), | ||
(18, 1,), | ||
(21, 1,), | ||
(26, 1,), | ||
(31, 1,), | ||
(35, 1,), | ||
] | ||
); | ||
let compressed_sequence = compress_sequence2(sequence); | ||
assert_eq!( | ||
compressed_sequence, | ||
vec![ | ||
0, 0, 9, 9, 2, 1, 1, 1, 7, 7, 7, -1, 4, 4, -1, 3, 3, 3, -1, -1, -1, -1, 5, 5, 5, 5, | ||
-1, 6, 6, 6, 6, -1, -1, -1, -1, -1, 8, 8, 8, 8, -1, -1, | ||
] | ||
); | ||
let check_sum = get_check_sum(compressed_sequence); | ||
assert_eq!(check_sum, 2858); | ||
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let result = part_two(&advent_of_code::template::read_file("examples", DAY)); | ||
assert_eq!(result, Some(2858)); | ||
} | ||
} |