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Complete day 10

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This commit is contained in:
Tristan Daniël Maat 2020-12-10 23:41:34 +00:00
parent af685599f5
commit 6921d46db3
Signed by: tlater
GPG key ID: 49670FD774E43268
5 changed files with 409 additions and 0 deletions
day-10/src
main.rs

225
day-10/src/main.rs Normal file
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use std::convert::TryInto;
use std::fs;
fn main() -> Result<(), Box<dyn std::error::Error>> {
let input = fs::read_to_string("input")?;
let jolts = parse_jolts(&input)?;
// Part 1
let result = chain_all(&jolts);
println!("{}", result.0 * result.1);
// Part 2
let result = count_possible_chains(&jolts)?;
println!("{}", result);
Ok(())
}
fn count_possible_chains(jolts: &Vec<u64>) -> Result<u64, std::num::TryFromIntError> {
let mut jolts = jolts.to_vec();
jolts.push(0);
jolts.sort();
jolts.push(jolts.last().expect("Need some jolts") + 3);
let window_lengths: Vec<usize> = jolts
.windows(2)
.scan(0, |length, window| {
if let [previous, current, _empty @ ..] = window {
if *current - *previous < 3 {
*length += 1;
Some(None)
} else {
let full_length = *length;
*length = 0;
Some(Some(full_length))
}
} else {
unreachable!("Window size is 2");
}
})
.filter_map(|option| option)
.collect();
fn permutations(length: u32) -> u64 {
if length == 0 {
1
} else {
2u64.pow(length - 1) - if length > 3 { 2u64.pow(length - 4) } else { 0 }
}
}
window_lengths
.iter()
.map(|length| Ok(permutations((*length).try_into()?)))
.product()
}
fn chain_all(jolts: &Vec<u64>) -> (usize, usize) {
let mut jolts = jolts.to_vec();
jolts.push(0);
jolts.sort();
jolts.push(jolts.last().expect("Need some jolts") + 3);
let jolt_jumps: Vec<u64> = jolts
.windows(2)
.map(|window| {
if let [first, second, _empty @ ..] = window {
second - first
} else {
unreachable!("Window size is 2");
}
})
.collect();
let jump_1s = jolt_jumps.iter().filter(|e| **e == 1).count();
let jump_3s = jolt_jumps.iter().filter(|e| **e == 3).count();
(jump_1s, jump_3s)
}
fn parse_jolts(input: &str) -> Result<Vec<u64>, std::num::ParseIntError> {
input.lines().map(|line| line.parse()).collect()
}
#[cfg(test)]
mod tests {
use super::*;
use indoc::indoc;
#[test]
fn test_simple() -> Result<(), Box<dyn std::error::Error>> {
let input = indoc!(
"16
10
15
5
1
11
7
19
6
12
4
"
);
let jolts = parse_jolts(input)?;
let result = chain_all(&jolts);
assert_eq!(result.0 * result.1, 7 * 5);
Ok(())
}
#[test]
fn test_simple2() -> Result<(), Box<dyn std::error::Error>> {
let input = indoc!(
"28
33
18
42
31
14
46
20
48
47
24
23
49
45
19
38
39
11
1
32
25
35
8
17
7
9
4
2
34
10
3
"
);
let jolts = parse_jolts(input)?;
let result = chain_all(&jolts);
assert_eq!(result.0 * result.1, 22 * 10);
Ok(())
}
#[test]
fn test_simple3() -> Result<(), Box<dyn std::error::Error>> {
let input = indoc!(
"16
10
15
5
1
11
7
19
6
12
4
"
);
let jolts = parse_jolts(input)?;
let result = count_possible_chains(&jolts)?;
assert_eq!(result, 8);
Ok(())
}
#[test]
fn test_simple4() -> Result<(), Box<dyn std::error::Error>> {
let input = indoc!(
"28
33
18
42
31
14
46
20
48
47
24
23
49
45
19
38
39
11
1
32
25
35
8
17
7
9
4
2
34
10
3
"
);
let jolts = parse_jolts(input)?;
let result = count_possible_chains(&jolts)?;
assert_eq!(result, 19208);
Ok(())
}
}