ishan/aoc2022
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Optimized day 9 part 2 by not inserting tail position if it hasn't changed

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This commit is contained in:
Ishan Jain 2022-12-09 19:57:57 +05:30
parent 8354241bbd
commit c739a665d3
Signed by: ishan
GPG Key ID: 0506DB2A1CC75C27
1 changed files with 8 additions and 3 deletions
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11
src/main.rs
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@ -1,8 +1,8 @@
#![feature(byte_slice_trim_ascii)] #![feature(byte_slice_trim_ascii)]
#![feature(test)] #![feature(test)]
extern crate test;
use std::collections::HashSet; use std::collections::HashSet;
extern crate test;
const INPUTS: [&[u8]; 2] = [ const INPUTS: [&[u8]; 2] = [
include_bytes!("../inputs/sample.txt"), include_bytes!("../inputs/sample.txt"),
@ -48,7 +48,8 @@ fn main() {
fn solution(input: Vec<Move>) -> usize { fn solution(input: Vec<Move>) -> usize {
let mut locs = [(0, 0); 10]; let mut locs = [(0, 0); 10];
let mut set: HashSet<(i32, i32)> = HashSet::with_capacity(3000); let mut set: HashSet<(i32, i32)> = HashSet::with_capacity_and_hasher(3000, Default::default());
set.insert((0, 0));
for mmove in input { for mmove in input {
let (steps, (dsxh, dsyh)) = match mmove { let (steps, (dsxh, dsyh)) = match mmove {
@ -58,6 +59,8 @@ fn solution(input: Vec<Move>) -> usize {
Move::D(v) => (v, (0, 1)), Move::D(v) => (v, (0, 1)),
}; };
let locs9 = locs[9];
for _ in 0..steps { for _ in 0..steps {
// Update Head position // Update Head position
locs[0].0 += dsxh; locs[0].0 += dsxh;
@ -72,7 +75,9 @@ fn solution(input: Vec<Move>) -> usize {
locs[i] = loci; locs[i] = loci;
} }
set.insert(locs[9]); if locs9 != locs[9] {
set.insert(locs[9]);
}
} }
} }