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use std::collections::HashMap;
use std::io::{self, Read};
fn solve1(input: i32) -> i32 {
let spiral = [(1, 0), (0, 1), (-1, 0), (0, -1)];
let (mut x, mut y) = (0i32, 0i32);
let mut n = 1;
for (i, &(dx, dy)) in spiral.iter().cycle().enumerate() {
let length = 1 + i / 2;
for _ in 0..length {
if n == input {
return x.abs() + y.abs();
}
n += 1;
x += dx;
y += dy;
}
}
unreachable!()
}
fn solve2(input: i32) -> i32 {
let spiral = [(1, 0), (0, 1), (-1, 0), (0, -1)];
let (mut x, mut y) = (0i32, 0i32);
let mut values = HashMap::new();
values.insert((0, 0), 1);
for (i, &(dx, dy)) in spiral.iter().cycle().enumerate() {
let length = 1 + i / 2;
for _ in 0..length {
let n =
values.get(&(x, y )).unwrap_or(&0) +
values.get(&(x - 1, y - 1)).unwrap_or(&0) +
values.get(&(x, y - 1)).unwrap_or(&0) +
values.get(&(x + 1, y - 1)).unwrap_or(&0) +
values.get(&(x + 1, y )).unwrap_or(&0) +
values.get(&(x + 1, y + 1)).unwrap_or(&0) +
values.get(&(x, y + 1)).unwrap_or(&0) +
values.get(&(x - 1, y + 1)).unwrap_or(&0) +
values.get(&(x - 1, y )).unwrap_or(&0);
values.insert((x, y), n);
if n > input {
return n;
}
x += dx;
y += dy;
}
}
unreachable!()
}
fn main() {
let mut input = String::new();
io::stdin().read_to_string(&mut input).unwrap();
println!("Part 1: {}", solve1(input.trim().parse().unwrap()));
println!("Part 2: {}", solve2(input.trim().parse().unwrap()));
}
#[test]
fn part1() {
assert_eq!(0, solve1(1));
assert_eq!(3, solve1(12));
assert_eq!(2, solve1(23));
assert_eq!(31, solve1(1024));
}
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