94 lines
2.6 KiB
Rust
94 lines
2.6 KiB
Rust
use crate::prelude::*;
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mod extra;
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use extra::*;
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pub fn solution() -> Solution {
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Solution::new(Day::new(12, 2020), part_1, part_2).with_expected(1496, 63843)
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}
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fn parse_instructions(input: &str) -> Vec<Instruction> {
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input.lines().map(Into::into).collect()
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}
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fn part_1(input: &str) -> Result<String> {
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let instructions = parse_instructions(input);
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let mut horizontal = 0;
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let mut vertical = 0;
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let mut direction: i32 = 90;
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for instruction in instructions {
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match instruction.action {
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Action::Forward => {
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match direction {
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90 => horizontal += instruction.value,
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270 => horizontal -= instruction.value,
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180 => vertical += instruction.value,
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0 => vertical -= instruction.value,
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_ => unreachable!("{direction}"),
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};
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}
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Action::Left => direction -= instruction.value,
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Action::Right => direction += instruction.value,
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Action::East => horizontal += instruction.value,
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Action::West => horizontal -= instruction.value,
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Action::South => vertical += instruction.value,
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Action::North => vertical -= instruction.value,
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};
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direction = match direction % 360 {
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-270 => 90,
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-90 => 270,
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0 => 0,
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value => value.abs(),
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};
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}
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Ok((horizontal.abs() + vertical.abs()).to_string())
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}
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fn part_2(input: &str) -> Result<String> {
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let instructions = parse_instructions(input);
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let mut horizontal = 0;
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let mut vertical = 0;
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let mut wp_horizontal = 10;
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let mut wp_vertical = -1;
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for instruction in instructions {
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match instruction.action {
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Action::Forward => {
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horizontal += wp_horizontal * instruction.value;
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vertical += wp_vertical * instruction.value;
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}
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Action::East => wp_horizontal += instruction.value,
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Action::West => wp_horizontal -= instruction.value,
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Action::South => wp_vertical += instruction.value,
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Action::North => wp_vertical -= instruction.value,
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_ => (),
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};
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match (&instruction.action, instruction.value) {
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(Action::Left, 90) | (Action::Right, 270) => {
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let intermediate_vertical = wp_vertical;
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wp_vertical = -wp_horizontal;
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wp_horizontal = intermediate_vertical;
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}
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(Action::Left, 180) | (Action::Right, 180) => {
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wp_horizontal = -wp_horizontal;
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wp_vertical = -wp_vertical;
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}
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(Action::Left, 270) | (Action::Right, 90) => {
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let intermediate_horizontal = wp_horizontal;
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wp_horizontal = -wp_vertical;
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wp_vertical = intermediate_horizontal;
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}
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_ => (),
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};
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}
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Ok((horizontal.abs() + vertical.abs()).to_string())
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}
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