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day4: do a lot fewer allocations, performance improvement x10

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This commit is contained in:
Keenan Tims 2024-12-03 22:07:01 -08:00
parent a81904f2eb
commit e5faee3470
Signed by: ktims
GPG Key ID: 11230674D69038D4
1 changed files with 10 additions and 11 deletions
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21
4/src/main.rs
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@ -68,7 +68,7 @@ impl WordSearch {
fn count_vertical(&self, needle: &str) -> u64 { fn count_vertical(&self, needle: &str) -> u64 {
let mut count = 0; let mut count = 0;
for col in 0..self.rows[0].len() { for col in 0..self.rows[0].len() {
let s: String = self.rows.iter().map(|row| row.chars().nth(col).unwrap()).collect(); let s: String = self.rows.iter().map(|row| row.as_bytes()[col] as char).collect();
count += Self::count_occurences(&s, needle) count += Self::count_occurences(&s, needle)
} }
count count
@ -82,21 +82,19 @@ impl WordSearch {
for y in 0..height { for y in 0..height {
// check down-right // check down-right
if x <= width - needle.len() && y <= height - needle.len() { if x <= width - needle.len() && y <= height - needle.len() {
let s: String = (0..needle.len()) if (0..needle.len())
.into_iter() .into_iter()
.map(|i| self.rows[y + i].chars().nth(x + i).unwrap()) .all(|i| self.get(x + i, y + i) == needle.as_bytes()[i].into())
.collect(); {
if s == needle {
count += 1 count += 1
} }
} }
// check down-left // check down-left
if x >= needle.len() - 1 && y <= height - needle.len() { if x >= needle.len() - 1 && y <= height - needle.len() {
let s: String = (0..needle.len()) if (0..needle.len())
.into_iter() .into_iter()
.map(|i| self.rows[y + i].chars().nth(x - i).unwrap()) .all(|i| self.get(x - i, y + i) == needle.as_bytes()[i].into())
.collect(); {
if s == needle {
count += 1 count += 1
} }
} }
@ -106,14 +104,15 @@ impl WordSearch {
} }
fn get(&self, x: usize, y: usize) -> char { fn get(&self, x: usize, y: usize) -> char {
self.rows[y].chars().nth(x).unwrap() self.rows[y].as_bytes()[x].into()
} }
fn count_x_mas(&self) -> u64 { fn count_x_mas(&self) -> u64 {
// M.M M.S S.M S.S // M.M M.S S.M S.S
// .A. .A. .A. .A. // .A. .A. .A. .A.
// S.S M.S S.M M.M // S.S M.S S.M M.M
let searches: [[char;5]; 4] = ["MMASS", "MSAMS", "SMASM", "SSAMM"].map(|s| s.chars().collect::<Vec<char>>().try_into().unwrap()); let searches: [[char; 5]; 4] =
["MMASS", "MSAMS", "SMASM", "SSAMM"].map(|s| s.chars().collect::<Vec<char>>().try_into().unwrap());
let width = self.rows[0].len(); let width = self.rows[0].len();
let height = self.rows.len(); let height = self.rows.len();