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use std::io::BufReader;
use std::io::prelude::*;
use std::fs::File;
fn main() {
let lines = read_file();
let mut current = '5';
for line in lines {
current = line.chars().fold(current, |current, dir| move_char_2(current, dir));
println!("{}", current);
}
}
fn read_file() -> Vec<String> {
let file = BufReader::new(File::open("input.txt").unwrap());
file.lines()
.map(|line| line.unwrap().trim().to_string())
.filter(|line| line.len() > 0)
.collect()
}
//assume current in 1-9 range, and char is in UDLR
fn move_char(current: i32, dir: char) -> i32 {
match dir {
'U' => if current <= 3 { current } else { current - 3},
'D' => if current >= 7 { current } else { current + 3},
'L' => if current%3 == 1 { current } else { current - 1},
'R' => if current%3 == 0 { current } else { current + 1},
_ => panic!("Bad direction character")
}
}
// 1
// 2 3 4
// 5 6 7 8 9
// A B C
// D
fn move_char_2(current: char, dir: char) -> char {
match dir {
'U' => match current {
'1'|'2'|'4'|'5'|'9' => current,
'3' => '1',
'6' => '2',
'7' => '3',
'8' => '4',
'A' => '6',
'B' => '7',
'C' => '8',
'D' => 'B',
_ => panic!("Bad current char")
},
'D' => match current {
'A'|'D'|'C'|'5'|'9' => current,
'1' => '3',
'2' => '6',
'3' => '7',
'4' => '8',
'6' => 'A',
'7' => 'B',
'8' => 'C',
'B' => 'D',
_ => panic!("Bad current char")
},
'L' => match current {
'1'|'2'|'5'|'A'|'D' => current,
'3' => '2',
'4' => '3',
'6' => '5',
'7' => '6',
'8' => '7',
'9' => '8',
'B' => 'A',
'C' => 'B',
_ => panic!("Bad current char")
},
'R' => match current {
'1'|'4'|'9'|'C'|'D' => current,
'2' => '3',
'3' => '4',
'5' => '6',
'6' => '7',
'7' => '8',
'8' => '9',
'A' => 'B',
'B' => 'C',
_ => panic!("Bad current char")
},
_ => panic!("Bad direction character")
}
}
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