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Day 15, switch to vec for more performance

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This commit is contained in:
Daniel S. 2020-12-16 20:18:23 +01:00
parent ce55569030
commit 739b17dd32
1 changed files with 4 additions and 5 deletions
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9
src/day15.rs
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@ -1,9 +1,8 @@
use aoc_runner_derive::{aoc, aoc_generator}; use aoc_runner_derive::{aoc, aoc_generator};
use std::collections::BTreeMap; use std::collections::HashMap;
use std::{collections::VecDeque, io::Write};
type Data = Vec<usize>; type Data = Vec<usize>;
#[derive(Debug)] #[derive(Debug,Clone)]
enum Seen { enum Seen {
Never, Never,
Once(usize), Once(usize),
@ -45,11 +44,11 @@ pub fn input_generator(input: &str) -> Data {
} }
fn get_number(start: &[usize], num_turns: usize) -> usize { fn get_number(start: &[usize], num_turns: usize) -> usize {
let mut cache: BTreeMap<usize, Seen> = BTreeMap::new(); let mut cache = vec![Seen::Never;num_turns];
let mut nums = start.to_vec(); let mut nums = start.to_vec();
let mut num=std::usize::MAX; let mut num=std::usize::MAX;
for i in 1..num_turns { for i in 1..num_turns {
num = cache.entry(nums[i - 1]).or_default().add(i); num = cache[nums[i - 1]].add(i);
if i >= nums.len() { if i >= nums.len() {
nums.push(num); nums.push(num);
} }