make 2020/10 slightly less ugly
This commit is contained in:
parent
5db6b005f9
commit
c2ed410f39
|
@ -1,11 +1,13 @@
|
||||||
#![feature(test)]
|
#![feature(test)]
|
||||||
extern crate test;
|
extern crate test;
|
||||||
use std::{env, iter};
|
use std::env;
|
||||||
|
|
||||||
use itertools::Itertools;
|
use itertools::Itertools;
|
||||||
|
|
||||||
type Parsed = Vec<usize>;
|
type Parsed = Vec<usize>;
|
||||||
|
|
||||||
|
const STEP_SIZE: usize = 3;
|
||||||
|
|
||||||
fn read_input() -> String {
|
fn read_input() -> String {
|
||||||
std::fs::read_to_string(
|
std::fs::read_to_string(
|
||||||
env::args()
|
env::args()
|
||||||
|
@ -18,35 +20,30 @@ fn read_input() -> String {
|
||||||
|
|
||||||
fn parse_input(raw: &str) -> Parsed {
|
fn parse_input(raw: &str) -> Parsed {
|
||||||
let mut xs: Vec<usize> = raw.lines().map(|l| l.parse().unwrap()).collect();
|
let mut xs: Vec<usize> = raw.lines().map(|l| l.parse().unwrap()).collect();
|
||||||
|
xs.push(0);
|
||||||
// faster than using sorted() directly on the iterator
|
// faster than using sorted() directly on the iterator
|
||||||
xs.sort_unstable();
|
xs.sort_unstable();
|
||||||
xs
|
xs
|
||||||
}
|
}
|
||||||
|
|
||||||
fn part1(input: &Parsed) -> (usize, usize) {
|
fn part1(input: &Parsed) -> (usize, usize) {
|
||||||
iter::once(&0)
|
input.iter().tuple_windows().fold((0, 1), |(one, three), (a, b)| match b - a {
|
||||||
.chain(input.iter())
|
1 => (one + 1, three),
|
||||||
.tuple_windows()
|
2 => (one, three),
|
||||||
.fold((0, 1), |(one, three), (a, b)| match b - a {
|
3 => (one, three + 1),
|
||||||
1 => (one + 1, three),
|
_ => unreachable!(),
|
||||||
2 => (one, three),
|
})
|
||||||
3 => (one, three + 1),
|
|
||||||
_ => unreachable!(),
|
|
||||||
})
|
|
||||||
}
|
}
|
||||||
|
|
||||||
fn part2(input: &Parsed) -> usize {
|
fn part2(input: &Parsed) -> usize {
|
||||||
let max = *input.last().unwrap();
|
let mut iter = input.iter().rev();
|
||||||
let mut paths = vec![0; max + 4];
|
let max = *iter.next().unwrap();
|
||||||
|
let mut paths = vec![0; max + STEP_SIZE];
|
||||||
paths[max] = 1;
|
paths[max] = 1;
|
||||||
for i in input.iter().rev().skip(1) {
|
for &i in iter {
|
||||||
let mut n = 0;
|
paths[i] = (1..=STEP_SIZE).map(|j| paths[i + j]).sum();
|
||||||
for j in 1..=3 {
|
|
||||||
n += paths[i + j];
|
|
||||||
}
|
|
||||||
paths[*i] = n;
|
|
||||||
}
|
}
|
||||||
paths[1] + paths[2] + paths[3]
|
paths[0]
|
||||||
}
|
}
|
||||||
|
|
||||||
fn main() {
|
fn main() {
|
||||||
|
|
Loading…
Reference in New Issue
Block a user