Complete day 9

pull/8/head
Tristan Daniël Maat 2020-12-09 21:15:37 +00:00
parent 49edaf0ae1
commit af685599f5
Signed by: tlater
GPG Key ID: 49670FD774E43268
5 changed files with 1240 additions and 0 deletions

1
day-9/.gitignore vendored Normal file
View File

@ -0,0 +1 @@
/target/

94
day-9/Cargo.lock generated Normal file
View File

@ -0,0 +1,94 @@
# This file is automatically @generated by Cargo.
# It is not intended for manual editing.
[[package]]
name = "day-9"
version = "0.1.0"
dependencies = [
"indoc",
"itertools",
]
[[package]]
name = "either"
version = "1.6.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "e78d4f1cc4ae33bbfc157ed5d5a5ef3bc29227303d595861deb238fcec4e9457"
[[package]]
name = "indoc"
version = "0.3.6"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "47741a8bc60fb26eb8d6e0238bbb26d8575ff623fdc97b1a2c00c050b9684ed8"
dependencies = [
"indoc-impl",
"proc-macro-hack",
]
[[package]]
name = "indoc-impl"
version = "0.3.6"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "ce046d161f000fffde5f432a0d034d0341dc152643b2598ed5bfce44c4f3a8f0"
dependencies = [
"proc-macro-hack",
"proc-macro2",
"quote",
"syn",
"unindent",
]
[[package]]
name = "itertools"
version = "0.9.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "284f18f85651fe11e8a991b2adb42cb078325c996ed026d994719efcfca1d54b"
dependencies = [
"either",
]
[[package]]
name = "proc-macro-hack"
version = "0.5.19"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "dbf0c48bc1d91375ae5c3cd81e3722dff1abcf81a30960240640d223f59fe0e5"
[[package]]
name = "proc-macro2"
version = "1.0.24"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "1e0704ee1a7e00d7bb417d0770ea303c1bccbabf0ef1667dae92b5967f5f8a71"
dependencies = [
"unicode-xid",
]
[[package]]
name = "quote"
version = "1.0.7"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "aa563d17ecb180e500da1cfd2b028310ac758de548efdd203e18f283af693f37"
dependencies = [
"proc-macro2",
]
[[package]]
name = "syn"
version = "1.0.54"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "9a2af957a63d6bd42255c359c93d9bfdb97076bd3b820897ce55ffbfbf107f44"
dependencies = [
"proc-macro2",
"quote",
"unicode-xid",
]
[[package]]
name = "unicode-xid"
version = "0.2.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f7fe0bb3479651439c9112f72b6c505038574c9fbb575ed1bf3b797fa39dd564"
[[package]]
name = "unindent"
version = "0.1.7"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f14ee04d9415b52b3aeab06258a3f07093182b88ba0f9b8d203f211a7a7d41c7"

11
day-9/Cargo.toml Normal file
View File

@ -0,0 +1,11 @@
[package]
name = "day-9"
version = "0.1.0"
authors = ["Tristan Daniël Maat <tm@tlater.net>"]
edition = "2018"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
indoc = "0.3"
itertools = "0.9"

1000
day-9/input Normal file

File diff suppressed because it is too large Load Diff

134
day-9/src/main.rs Normal file
View File

@ -0,0 +1,134 @@
use std::fs;
use std::num::ParseIntError;
use itertools::{Itertools, MinMaxResult};
fn main() -> Result<(), Box<dyn std::error::Error>> {
let input = fs::read_to_string("input")?;
let xmas = parse_xmas(&input)?;
// Part 1
let result = find_not_summed(&xmas, 25)?;
println!("{}", result);
// Part 2
let result = find_weakness(&xmas, result)?;
println!("{}", result);
Ok(())
}
fn parse_xmas(input: &str) -> Result<Vec<u64>, ParseIntError> {
input.lines().map(|line| line.parse()).collect()
}
fn find_weakness(xmas: &Vec<u64>, key: u64) -> Result<u64, &str> {
// Now we use the key to find the weakness, by getting all
// possible sub-sumbs of the list of numbers, and finding the one
// that happens to match our key
let weak_window = (2..xmas.len())
.find_map(|window_size| {
xmas.windows(window_size)
.find(|window| window.iter().sum::<u64>() == key)
})
.ok_or("Could not find a weakness")?;
if let MinMaxResult::MinMax(min, max) = weak_window.iter().minmax() {
Ok(min + max)
} else {
unreachable!("We must have at least two elements due to the window size")
}
}
fn find_not_summed(xmas: &Vec<u64>, window_size: usize) -> Result<u64, &str> {
xmas.windows(window_size + 1)
.find_map(|window| {
if let [preamble @ .., number] = window {
// If none of the number combinations in the preamble
// sum to the final number, we've got the key!
if !preamble
.iter()
.combinations(2)
.any(|combination| combination.into_iter().sum::<u64>() == *number)
{
Some(*number)
} else {
None
}
} else {
unreachable!("The windows must all have a length of at least 1");
}
})
.ok_or("Could not find the entry")
}
#[cfg(test)]
mod tests {
use super::*;
use indoc::indoc;
#[test]
fn test_simple() -> Result<(), Box<dyn std::error::Error>> {
let input = indoc!(
"35
20
15
25
47
40
62
55
65
95
102
117
150
182
127
219
299
277
309
576"
);
let xmas = parse_xmas(input)?;
let result = find_not_summed(&xmas, 5)?;
assert_eq!(result, 127);
Ok(())
}
#[test]
fn test_simple2() -> Result<(), Box<dyn std::error::Error>> {
let input = indoc!(
"35
20
15
25
47
40
62
55
65
95
102
117
150
182
127
219
299
277
309
576"
);
let xmas = parse_xmas(input)?;
let key = find_not_summed(&xmas, 5)?;
let result = find_weakness(&xmas, key)?;
assert_eq!(result, 62);
Ok(())
}
}