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static DAY: u8 = 20;
fn main() {
let input = advent::read_lines(DAY);
println!("{DAY}a: {}", grove_coordinates(&input));
println!("{DAY}b: {}", 0);
}
fn grove_coordinates(input: &[String]) -> isize {
let mut input = input.iter()
.map(|x| (x.parse::<isize>().unwrap(), false))
.collect::<Vec<_>>();
loop {
let pos = match input.iter().position(|x| !x.1) {
None => break,
Some(p) => p,
};
let val = input[pos];
input.remove(pos);
let input_len = input.len() as isize;
let pos_diff = val.0 % input_len;
let mut new_pos = (pos as isize + pos_diff) % input_len;
if new_pos.is_negative() {
new_pos += input_len;
}
if new_pos == 0 {
input.push((val.0 as isize, true));
} else {
input.insert(new_pos as usize, (val.0 as isize, true));
}
}
let pos = input.iter().position(|x| x.0 == 0).unwrap();
let n = ((pos + 1000) % input.len(), (pos + 2000) % input.len(), (pos + 3000) % input.len());
input[n.0].0 + input[n.1].0 + input[n.2].0
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
let input = [
"1",
"2",
"-3",
"3",
"-2",
"0",
"4",
].iter().map(|&x| String::from(x)).collect::<Vec<_>>();
assert_eq!(grove_coordinates(&input), 3);
}
}
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