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extern crate advent_of_code_2017;
use advent_of_code_2017::*;
fn main() {
use Direction::*;
let args = AdventArgs::init();
let input: Vec<Vec<char>> = args.input.iter().map(|line| line.chars().collect()).collect();
let mut position = Point {
x: input[0].iter().position(|&c| c == '|').unwrap() as i32,
y: 0
};
let mut direction = Down;
let mut path_ended = false;
let mut tokens = Vec::new();
// moving onto the map counts as one, but because of how I'm
// counting there's also an off the map step that I shouldn't be
// counting at the end. They cancel out.
let mut steps_moved = 0;
while !path_ended {
position = position.shift(&direction);
steps_moved += 1;
match char_at(&input, &position) {
'|' | '-' => {
//continue as is
},
' ' => {
path_ended = true;
},
'+' => {
let left_option = char_at(&input, &position.shift(&direction.rotate_left()));
let right_option = char_at(&input, &position.shift(&direction.rotate_right()));
match (left_option, right_option) {
(' ', ' ') => {
path_ended = true;
},
(_, ' ') => {
direction = direction.rotate_left();
},
(' ', _) => {
direction = direction.rotate_right();
},
_ => {
panic!("Don't know where to go from {:?}", position);
}
}
},
token => {
tokens.push(token);
}
}
}
if args.part == 1 {
println!("{}", tokens.iter().collect::<String>());
} else {
println!("{}", steps_moved);
}
}
fn char_at(input: &Vec<Vec<char>>, position: &Point) -> char {
if position.y < 0 ||
position.x < 0 ||
position.y as usize >= input.len() ||
position.x as usize >= input[position.y as usize].len() {
' '
} else {
input[position.y as usize][position.x as usize]
}
}
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