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use std::fs;
fn solve_part1(lines: &Vec<&str>) -> usize {
let mut total_tls = 0;
for line in lines {
let chars: Vec<char> = line.chars().collect();
let mut has_tls = false;
let mut in_brackets = false;
for i in 0..chars.len() - 3 {
// Are we entering/leaving a "hypernet sequence"?
if chars[i] == '[' {
in_brackets = true;
} else if chars[i] == ']' {
in_brackets = false;
}
// Check for ABBA pattern to know if address has TLS
let ch0 = chars[i];
let ch1 = chars[i + 1];
if ch0 != ch1 && chars[i + 3] == ch0 && chars[i + 2] == ch1 {
if !in_brackets {
has_tls = true;
} else {
// Reject if an ABBA occurs in brackets
has_tls = false;
break;
}
}
}
if has_tls {
total_tls += 1;
}
}
total_tls
}
fn solve_part2(lines: &Vec<&str>) -> usize {
let mut total_ssl = 0;
for line in lines {
let chars: Vec<char> = line.chars().collect();
let mut has_ssl = false;
let mut in_brack_aba = false;
'outer: for i in 0..chars.len() - 2 {
// Are we entering/leaving brackets on our ABA search?
if chars[i] == '[' {
in_brack_aba = true;
} else if chars[i] == ']' {
in_brack_aba = false;
}
// Check for ABA pattern
let ch0 = chars[i];
let ch1 = chars[i + 1];
if !in_brack_aba && ch0 != ch1 && chars[i + 2] == ch0 {
// If ABA was found, check entire address for BAB
let mut in_brack_bab = false;
for j in 0..chars.len() - 2 {
// Are we entering/leaving brackets on our BAB search?
if chars[j] == '[' {
in_brack_bab = true;
} else if chars[j] == ']' {
in_brack_bab = false;
}
if chars[j] == ch1 && chars[j + 1] == ch0 && chars[j + 2] == ch1 {
// BAB must be in square brackets
if in_brack_bab {
has_ssl = true;
break 'outer;
}
}
}
}
}
if has_ssl {
total_ssl += 1;
}
}
total_ssl
}
fn main() {
// Read address list from input text file
let input = fs::read_to_string("input.txt").unwrap();
let lines = input.lines().collect();
// Part 1 gives 118 for me
println!("Part 1 solution: {}", solve_part1(&lines));
// Part 2 gives 260 for me
println!("Part 2 solution: {}", solve_part2(&lines));
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn part1_example1() {
let lines = vec!["abba[mnop]qrst"];
assert_eq!(solve_part1(&lines), 1);
}
#[test]
fn part1_example2() {
let lines = vec!["abcd[bddb]xyyx"];
assert_eq!(solve_part1(&lines), 0);
}
#[test]
fn part1_example3() {
let lines = vec!["aaaa[qwer]tyui"];
assert_eq!(solve_part1(&lines), 0);
}
#[test]
fn part1_example4() {
let lines = vec!["ioxxoj[asdfgh]zxcvbn"];
assert_eq!(solve_part1(&lines), 1);
}
#[test]
fn part2_example1() {
let lines = vec!["aba[bab]xyz"];
assert_eq!(solve_part2(&lines), 1);
}
#[test]
fn part2_example2() {
let lines = vec!["xyx[xyx]xyx"];
assert_eq!(solve_part2(&lines), 0);
}
#[test]
fn part2_example3() {
let lines = vec!["aaa[kek]eke"];
assert_eq!(solve_part2(&lines), 1);
}
#[test]
fn part2_example4() {
let lines = vec!["zazbz[bzb]cdb"];
assert_eq!(solve_part2(&lines), 1);
}
}
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