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static DAY: u8 = 2;
fn main() {
let input = advent::read_lines(DAY);
println!("{DAY}a: {}", safe_reports(&input, false));
println!("{DAY}b: {}", safe_reports(&input, true));
}
fn is_report_safe(report: &[i32]) -> bool {
let increasing = report[1] - report[0] > 0;
for number in report.iter().as_slice().windows(2) {
let diff = number[1] - number[0];
if diff.abs() < 1 || diff.abs() > 3 {
return false;
}
if (diff > 0) != increasing {
return false;
}
}
true
}
fn safe_reports(input: &[String], with_dampener: bool) -> usize {
let mut reports = Vec::new();
for line in input {
let numbers = line.split(" ")
.map(|x| x.parse::<i32>().unwrap())
.collect::<Vec<_>>();
reports.push(numbers);
}
let mut count = 0;
for report in reports {
if is_report_safe(&report) {
count += 1;
} else if with_dampener {
for i in 0 .. report.len() {
let mut dampened = report.clone();
dampened.remove(i);
if is_report_safe(&dampened) {
count += 1;
break;
}
}
}
}
count
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
let input = [
"7 6 4 2 1",
"1 2 7 8 9",
"9 7 6 2 1",
"1 3 2 4 5",
"8 6 4 4 1",
"1 3 6 7 9",
].iter().map(|&x| String::from(x)).collect::<Vec<_>>();
assert_eq!(safe_reports(&input, false), 2);
assert_eq!(safe_reports(&input, true), 4);
}
}
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