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Rework day 1 solution to use one function for both parts

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This commit is contained in:
Wesley Moore 2017-12-03 09:26:33 +10:00
parent b35039cb2f
commit 3d6dd9c98e
1 changed files with 16 additions and 31 deletions
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47
2017/day/1/src/main.rs
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@ -6,34 +6,19 @@ fn main() {
let mut file = File::open("input").expect("unable to open input file");
file.read_to_end(&mut input).expect("error reading input");
println!("{}", captcha(&input));
println!("{}", captcha2(&input));
}
fn captcha(input: &[u8]) -> u64 {
let digits = input.iter()
.take_while(|&&chr| chr >= 0x30 && chr <= 0x39)
let digits = input.into_iter()
.take_while(|&chr| chr >= 0x30 && chr <= 0x39)
.collect::<Vec<_>>();
let mut sum = 0;
for idx in 0..digits.len() {
if digits[idx] == digits[(idx + 1) % digits.len()] {
sum += *digits[idx] as u64 - 0x30;
}
}
sum
println!("{}", captcha(digits.as_slice(), 1));
println!("{}", captcha(digits.as_slice(), digits.len() / 2));
}
fn captcha2(input: &[u8]) -> u64 {
let digits = input.iter()
.take_while(|&&chr| chr >= 0x30 && chr <= 0x39)
.collect::<Vec<_>>();
fn captcha(digits: &[u8], offset: usize) -> u64 {
let mut sum = 0;
for idx in 0..digits.len() {
if digits[idx] == digits[(idx + (digits.len() / 2)) % digits.len()] {
sum += *digits[idx] as u64 - 0x30;
if digits[idx] == digits[(idx + offset) % digits.len()] {
sum += digits[idx] as u64 - 0x30;
}
}
@ -44,54 +29,54 @@ fn captcha2(input: &[u8]) -> u64 {
// third digit (2) matches the fourth digit.
#[test]
fn test_captcha_example1() {
assert_eq!(captcha(b"1122"), 3);
assert_eq!(captcha(b"1122", 1), 3);
}
// 1111 produces 4 because each digit (all 1) matches the next.
#[test]
fn test_captcha_example2() {
assert_eq!(captcha(b"1111"), 4);
assert_eq!(captcha(b"1111", 1), 4);
}
// 1234 produces 0 because no digit matches the next.
#[test]
fn test_captcha_example3() {
assert_eq!(captcha(b"1234"), 0);
assert_eq!(captcha(b"1234", 1), 0);
}
// 91212129 produces 9 because the only digit that matches the next one is the last digit, 9.
#[test]
fn test_captcha_example4() {
assert_eq!(captcha(b"91212129"), 9);
assert_eq!(captcha(b"91212129", 1), 9);
}
// 1212 produces 6: the list contains 4 items, and all four digits match the digit 2 items ahead.
#[test]
fn test_captcha2_example1() {
assert_eq!(captcha2(b"1212"), 6);
assert_eq!(captcha(b"1212", 2), 6);
}
// 1221 produces 0, because every comparison is between a 1 and a 2.
#[test]
fn test_captcha2_example2() {
assert_eq!(captcha2(b"1221"), 0);
assert_eq!(captcha(b"1221", 2), 0);
}
// 123425 produces 4, because both 2s match each other, but no other digit has a match.
#[test]
fn test_captcha2_example3() {
assert_eq!(captcha2(b"123425"), 4);
assert_eq!(captcha(b"123425", 3), 4);
}
// 123123 produces 12.
#[test]
fn test_captcha2_example4() {
assert_eq!(captcha2(b"123123"), 12);
assert_eq!(captcha(b"123123", 3), 12);
}
// 12131415 produces 4.
#[test]
fn test_captcha2_example5() {
assert_eq!(captcha2(b"12131415"), 4);
assert_eq!(captcha(b"12131415", 4), 4);
}