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rust(day15): Optimize day 15 to ~450 ms

This commit is contained in:
Sijmen 2020-12-25 21:12:18 +01:00
parent fc9cfec98d
commit b8fd7080b6
Signed by: vijfhoek
GPG Key ID: DAF7821E067D9C48
1 changed files with 12 additions and 11 deletions
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23
rust/src/day15.rs
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@ -1,23 +1,24 @@
use std::time::{Duration, Instant}; use std::time::{Duration, Instant};
use std::boxed::Box;
const END: usize = 30_000_000; const END: u32 = 30_000_000;
pub fn run(print: bool) -> Duration { pub fn run(print: bool) -> Duration {
let input: Vec<usize> = "0,1,5,10,3,12,19" let input: Vec<u32> = "0,1,5,10,3,12,19"
.split(",") .split(",")
.map(|i| i.parse().unwrap()) .map(|i| i.parse().unwrap())
.collect(); .collect();
let instant = Instant::now(); let instant = Instant::now();
let mut history = vec![0; END]; let mut history = vec![0u32; END as usize];
let mut last = input[0]; let mut last = input[0];
for turn in 0..input.len() { for turn in 0..input.len() as u32 {
history[last] = turn; history[last as usize] = turn as u32;
last = input[turn]; last = input[turn as usize];
} }
for turn in input.len()..2020 { for turn in input.len() as u32..2020 {
let stored = history[last]; let stored = history[last as usize];
history[last] = turn; history[last as usize] = turn;
last = if stored == 0 { 0 } else { turn - stored }; last = if stored == 0 { 0 } else { turn - stored };
} }
if print { if print {
@ -25,8 +26,8 @@ pub fn run(print: bool) -> Duration {
} }
for turn in 2020..END { for turn in 2020..END {
let stored = history[last]; let stored = history[last as usize];
history[last] = turn; history[last as usize] = turn;
last = if stored == 0 { 0 } else { turn - stored }; last = if stored == 0 { 0 } else { turn - stored };
} }
if print { if print {