bert/adventofcode
1
0
Fork 0
mirror of https://github.com/bertptrs/adventofcode.git synced 2025-12-25 21:00:31 +01:00
Code Issues Projects Releases Wiki Activity

Rewrite using iterators

Browse Source 
This improves codegen for part 1 considerably.
This commit is contained in:
Bert Peters
2020-12-06 09:26:17 +01:00
parent ecade93f0f
commit 0bf021045c
1 changed files with 10 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
2020/src/day06.rs
View File

@@ -10,23 +10,18 @@ fn count(answers: Answers) -> u32 {
} }
fn compute_answers(group: &str) -> Answers { fn compute_answers(group: &str) -> Answers {
let mut questions = 0; group
.chars()
for question in group.chars().filter(char::is_ascii_lowercase) { .filter(char::is_ascii_lowercase)
questions |= 1 << (question as usize - 'a' as usize); .map(|q| 1 << (q as usize - 'a' as usize))
} .fold(0, |a, b| a | b)
questions
} }
fn count_answers_all(group: &str) -> u32 { fn count_answers_all(group: &str) -> u32 {
let mut combined = 0xffff_ffff; let combined = group
.split('\n')
for line in group.split('\n') { .map(compute_answers)
let single = compute_answers(line); .fold(0xffff_ffff, |a, b| a & b);
combined &= single;
}
count(combined) count(combined)
} }
@@ -38,7 +33,7 @@ impl Solution for Day06 {
fn part1(&mut self, input: &mut dyn Read) -> String { fn part1(&mut self, input: &mut dyn Read) -> String {
let input: String = read_single_input(input); let input: String = read_single_input(input);
let total: u32 = input.split("\n\n").map(compute_answers).map(count).sum(); let total: u32 = input.split("\n\n").map(|g| count(compute_answers(g))).sum();
total.to_string() total.to_string()
} }