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Stream to reduce peak allocations

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This commit is contained in:
Bert Peters
2022-12-13 18:22:26 +01:00
parent 4b18a733c9
commit f48a02c81c
1 changed files with 7 additions and 10 deletions
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17
2022/src/day13.rs
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@@ -6,6 +6,7 @@ use nom::branch::alt;
use nom::bytes::complete::tag; use nom::bytes::complete::tag;
use nom::character::complete::multispace1; use nom::character::complete::multispace1;
use nom::character::complete::newline; use nom::character::complete::newline;
use nom::combinator::iterator;
use nom::combinator::map; use nom::combinator::map;
use nom::multi::many0; use nom::multi::many0;
use nom::multi::separated_list0; use nom::multi::separated_list0;
@@ -72,21 +73,17 @@ fn parse_signal(input: &[u8]) -> IResult<&[u8], Signal> {
))(input) ))(input)
} }
fn parse_signal_pairs(input: &[u8]) -> IResult<&[u8], Vec<(Signal, Signal)>> { fn parse_signal_pair(input: &[u8]) -> IResult<&[u8], (Signal, Signal)> {
separated_list0( pair(
newline, terminated(parse_signal, newline),
pair( terminated(parse_signal, multispace1),
terminated(parse_signal, newline),
terminated(parse_signal, newline),
),
)(input) )(input)
} }
pub fn part1(input: &[u8]) -> Result<String> { pub fn part1(input: &[u8]) -> Result<String> {
let signals = parse_input(input, parse_signal_pairs)?; let mut iterator = iterator(input, parse_signal_pair);
let result: usize = signals let result: usize = (&mut iterator)
.into_iter()
.enumerate() .enumerate()
.filter_map(|(i, (first, second))| (first < second).then_some(i + 1)) .filter_map(|(i, (first, second))| (first < second).then_some(i + 1))
.sum(); .sum();