thallada/advent-of-code-2020
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Use binary ops instead of range in day 5

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This commit is contained in:
Tyler Hallada 2020-12-05 16:43:56 -05:00
parent 31b6323fcc
commit ff14ce2219
1 changed files with 10 additions and 17 deletions
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25
day05/src/main.rs
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@ -23,24 +23,17 @@ impl FromStr for Seat {
type Err = Error; type Err = Error;
fn from_str(s: &str) -> Result<Self> { fn from_str(s: &str) -> Result<Self> {
let row = s.chars().take(7).try_fold(0..128, |range, c| match c { let row = s.chars().take(7).try_fold(0, |row, c| match c {
'F' => Ok(range.start..(range.end - ((range.end - range.start) / 2))), 'F' => Ok(row << 1),
'B' => Ok((range.start + ((range.end - range.start) / 2))..range.end), 'B' => Ok(row << 1 | 1),
_ => Err(anyhow!("Unrecognized row character: {}", c)), _ => Err(anyhow!("Unrecognized row character: {}", c)),
})?; })?;
let col = s let col = s.chars().skip(7).take(3).try_fold(0, |col, c| match c {
.chars() 'L' => Ok(col << 1),
.skip(7) 'R' => Ok(col << 1 | 1),
.take(3) _ => Err(anyhow!("Unrecognized col character: {}", c)),
.try_fold(0..8, |range, c| match c {
'L' => Ok(range.start..(range.end - ((range.end - range.start) / 2))),
'R' => Ok((range.start + ((range.end - range.start) / 2))..range.end),
_ => Err(anyhow!("Unrecognized row character: {}", c)),
})?; })?;
Ok(Self { Ok(Self { row, col })
row: row.start,
col: col.start,
})
} }
} }
@ -53,7 +46,7 @@ fn solve_part1(input_path: &str) -> Result<u32> {
.map(|line| Seat::from_str(&line.unwrap()).unwrap()) .map(|line| Seat::from_str(&line.unwrap()).unwrap())
.map(|seat| seat.id()) .map(|seat| seat.id())
.max() .max()
.ok_or(anyhow!("No seats found in input"))?) .ok_or_else(|| anyhow!("No seats found in input"))?)
} }
fn solve_part2(input_path: &str) -> Result<u32> { fn solve_part2(input_path: &str) -> Result<u32> {