feat: add day 7

README.md

@@ -17,8 +17,9 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | [Day 4](./src/bin/04.rs) | `152.1ms` | `242.8ms` |
 | [Day 5](./src/bin/05.rs) | `5.1s` | `11.7s` |
 | [Day 6](./src/bin/06.rs) | `384.1µs` | `396.5µs` |
+| [Day 7](./src/bin/07.rs) | `1.5ms` | `1.3ms` |
 
-**Total: 17196.56ms**
+**Total: 17199.36ms**
 <!--- benchmarking table --->
 
 ---

data/examples/07.txt

@@ -0,0 +1,4 @@
+abba[mnop]qrst
+abcd[bddb]xyyx
+aaaa[qwer]tyui
+ioxxoj[asdfgh]zxcvbn

src/bin/07.rs

@@ -0,0 +1,96 @@
+advent_of_code::solution!(7);
+
+fn supports_tls(input: &&str) -> bool {
+    let input: Vec<char> = input.chars().collect();
+    let mut has_abba: bool = false;
+    let mut is_hypernet: bool = false;
+    for c in 0..(input.len() - 3) {
+        match input[c] {
+            '[' => is_hypernet = true,
+            ']' => is_hypernet = false,
+            _ => {
+                if input[c] == input[c + 3]
+                    && input[c + 1] == input[c + 2]
+                    && input[c] != input[c + 1]
+                {
+                    if is_hypernet {
+                        return false;
+                    }
+                    has_abba = true;
+                }
+            }
+        }
+    }
+    has_abba
+}
+
+fn supports_ssl(input: &&str) -> bool {
+    let input: Vec<char> = input.chars().collect();
+    let mut is_hypernet: bool = false;
+    let mut abas: Vec<(char, char)> = Vec::new();
+    let mut babs: Vec<(char, char)> = Vec::new();
+
+    for c in 0..(input.len() - 2) {
+        match input[c] {
+            '[' => is_hypernet = true,
+            ']' => is_hypernet = false,
+            _ => {
+                if input[c] == input[c + 2]
+                    && input[c + 1] != input[c]
+                    && input[c + 1] != '['
+                    && input[c + 1] != ']'
+                {
+                    let pair = (input[c], input[c + 1]);
+                    if is_hypernet {
+                        babs.push(pair);
+                    } else {
+                        abas.push(pair);
+                    }
+                }
+            }
+        }
+    }
+
+    for pat in abas {
+        let rev_pat = (pat.1, pat.0);
+        if babs.contains(&rev_pat) {
+            return true;
+        }
+    }
+    false
+}
+
+fn count_matching_ips(input: &str, func: &dyn Fn(&&str) -> bool) -> Option<usize> {
+    input
+        .strip_suffix("\n")
+        .unwrap_or(input)
+        .split("\n")
+        .filter(func)
+        .count()
+        .into()
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    count_matching_ips(input, &supports_tls)
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    count_matching_ips(input, &supports_ssl)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(2));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(3));
+    }
+}