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Commit 49af580

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Year 2017 speed and code quality improvements
1 parent 73acfe5 commit 49af580

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5 files changed

+39
-26
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5 files changed

+39
-26
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‎README.md

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -302,14 +302,14 @@ Performance is reasonable even on older hardware, for example a 2011 MacBook Pro
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| 1 | [Inverse Captcha](https://adventofcode.com/2017/day/1) | [Source](src/year2017/day01.rs) | 1 |
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| 2 | [Corruption Checksum](https://adventofcode.com/2017/day/2) | [Source](src/year2017/day02.rs) | 2 |
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| 3 | [Spiral Memory](https://adventofcode.com/2017/day/3) | [Source](src/year2017/day03.rs) | 2 |
305-
| 4 | [High-Entropy Passphrases](https://adventofcode.com/2017/day/4) | [Source](src/year2017/day04.rs) | 98 |
305+
| 4 | [High-Entropy Passphrases](https://adventofcode.com/2017/day/4) | [Source](src/year2017/day04.rs) | 86 |
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| 5 | [A Maze of Twisty Trampolines, All Alike](https://adventofcode.com/2017/day/5) | [Source](src/year2017/day05.rs) | 22000 |
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| 6 | [Memory Reallocation](https://adventofcode.com/2017/day/6) | [Source](src/year2017/day06.rs) | 81 |
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| 7 | [Recursive Circus](https://adventofcode.com/2017/day/7) | [Source](src/year2017/day07.rs) | 93 |
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| 8 | [I Heard You Like Registers](https://adventofcode.com/2017/day/8) | [Source](src/year2017/day08.rs) | 47 |
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| 9 | [Stream Processing](https://adventofcode.com/2017/day/9) | [Source](src/year2017/day09.rs) | 23 |
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| 10 | [Knot Hash](https://adventofcode.com/2017/day/10) | [Source](src/year2017/day10.rs) | 66 |
312-
| 11 | [Hex Ed](https://adventofcode.com/2017/day/11) | [Source](src/year2017/day11.rs) | 18 |
312+
| 11 | [Hex Ed](https://adventofcode.com/2017/day/11) | [Source](src/year2017/day11.rs) | 15 |
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| 12 | [Digital Plumber](https://adventofcode.com/2017/day/12) | [Source](src/year2017/day12.rs) | 61 |
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| 13 | [Packet Scanners](https://adventofcode.com/2017/day/13) | [Source](src/year2017/day13.rs) | 1 |
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| 14 | [Disk Defragmentation](https://adventofcode.com/2017/day/14) | [Source](src/year2017/day14.rs) | 438 |
@@ -321,7 +321,7 @@ Performance is reasonable even on older hardware, for example a 2011 MacBook Pro
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| 20 | [Particle Swarm](https://adventofcode.com/2017/day/20) | [Source](src/year2017/day20.rs) | 245 |
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| 21 | [Fractal Art](https://adventofcode.com/2017/day/21) | [Source](src/year2017/day21.rs) | 5 |
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| 22 | [Sporifica Virus](https://adventofcode.com/2017/day/22) | [Source](src/year2017/day22.rs) | 36000 |
324-
| 23 | [Coprocessor Conflagration](https://adventofcode.com/2017/day/23) | [Source](src/year2017/day23.rs) | 19 |
324+
| 23 | [Coprocessor Conflagration](https://adventofcode.com/2017/day/23) | [Source](src/year2017/day23.rs) | 16 |
325325
| 24 | [Electromagnetic Moat](https://adventofcode.com/2017/day/24) | [Source](src/year2017/day24.rs) | 275 |
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| 25 | [The Halting Problem](https://adventofcode.com/2017/day/25) | [Source](src/year2017/day25.rs) | 3698 |
327327

‎src/year2017/day02.rs

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -19,17 +19,17 @@ pub fn parse(input: &str) -> Input {
1919
}
2020

2121
pub fn part1(input: &Input) -> u32 {
22-
input.iter().map(|values| values[values.len() - 1] - values[0]).sum()
22+
input.iter().map(|values| values.last().unwrap() - values.first().unwrap()).sum()
2323
}
2424

2525
pub fn part2(input: &Input) -> u32 {
2626
input
2727
.iter()
2828
.map(|values| {
29-
for i in 0..values.len() {
30-
for j in i + 1..values.len() {
31-
if values[j].is_multiple_of(values[i]) {
32-
return values[j] / values[i];
29+
for (i,&smaller)in values.iter().enumerate() {
30+
for &larger in &values[i + 1..] {
31+
if larger.is_multiple_of(smaller) {
32+
return larger / smaller;
3333
}
3434
}
3535
}

‎src/year2017/day04.rs

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -32,9 +32,9 @@ pub fn part1(input: &Input<'_>) -> usize {
3232
}
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3434
pub fn part2(input: &Input<'_>) -> usize {
35-
// Calculate the frequency of each letter as anagrams will have the same values.
36-
fn convert(token: &str) -> [u8; 26] {
37-
let mut freq = [0; 26];
35+
// Only 26 elements are needed but 32 is faster to hash.
36+
fn convert(token: &str) -> [u8; 32] {
37+
let mut freq = [0; 32];
3838
for b in token.bytes() {
3939
freq[(b - b'a') as usize] += 1;
4040
}

‎src/year2017/day11.rs

Lines changed: 16 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -16,24 +16,32 @@ pub fn parse(input: &str) -> Input {
1616
let mut part_two = 0;
1717

1818
while let Some(first) = iter.next() {
19-
match first {
20-
b'n' => match iter.next().unwrap_or(0) {
19+
if first == b'n' {
20+
match iter.next().unwrap_or(0) {
2121
b'e' => {
22+
iter.next(); // Consume trailing delimeter.
2223
q += 1;
2324
r -= 1;
2425
}
25-
b'w' => q -= 1,
26+
b'w' => {
27+
iter.next(); // Consume trailing delimeter.
28+
q -= 1;
29+
}
2630
_ => r -= 1,
27-
},
28-
b's' => match iter.next().unwrap_or(0) {
29-
b'e' => q += 1,
31+
}
32+
} else {
33+
match iter.next().unwrap_or(0) {
34+
b'e' => {
35+
iter.next(); // Consume trailing delimeter.
36+
q += 1;
37+
}
3038
b'w' => {
39+
iter.next(); // Consume trailing delimeter.
3140
q -= 1;
3241
r += 1;
3342
}
3443
_ => r += 1,
35-
},
36-
_ => (),
44+
}
3745
}
3846

3947
// q + r + s = 0, so we can always determine s given the other two.

‎src/year2017/day23.rs

Lines changed: 12 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -58,25 +58,30 @@ pub fn parse(input: &str) -> u32 {
5858

5959
/// The number of `mul` operations is `(n - 2)2`
6060
pub fn part1(input: &u32) -> u32 {
61-
(input - 2) * (input - 2)
61+
let n = input - 2;
62+
n * n
6263
}
6364

6465
/// Count the number of composite numbers in a range calculated from the input number.
6566
pub fn part2(input: &u32) -> usize {
66-
(0..=1000).filter_map(|n| composite(100_000 + 100 * input + 17 * n)).count()
67+
let start = 100_000 + 100 * input;
68+
let end = start + 17001;
69+
(start..end).step_by(17).filter(|&n| is_composite(n)).count()
6770
}
6871

6972
/// Simple [prime number check](https://en.wikipedia.org/wiki/Primality_test)
7073
/// of all factors from 2 to √n inclusive.
71-
fn composite(n: u32) -> Option<u32> {
74+
fn is_composite(n: u32) -> bool {
7275
if n.is_multiple_of(2) {
73-
return Some(n);
76+
return true;
7477
}
75-
for f in (3..).step_by(2).take_while(|m| m * m <= n) {
78+
79+
let root = n.isqrt() + 1;
80+
for f in (3..root).step_by(2) {
7681
if n.is_multiple_of(f) {
77-
return Some(n);
82+
return true;
7883
}
7984
}
8085

81-
None
86+
false
8287
}

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