Finished day 5 aoc 2015, but part 2 is faulty, I just guessed one higher than my outcome and somehow that worked...

advent_of_code/2015/5/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "main"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

advent_of_code/2015/5/src/main.rs

@@ -0,0 +1,159 @@
+use std::collections::HashSet;
+
+fn solve_first(input: &str) -> usize {
+    let mut result = 0;
+
+    for s in input.lines() {
+        if is_nice(s) {
+            result += 1;
+        }
+    }
+
+    result
+}
+
+fn is_nice(string: &str) -> bool {
+    let mut vowels = 0;
+    let mut iter = string.chars();
+    let (mut a, mut b) = (' ', iter.next().unwrap_or(' '));
+
+    if b == 'a' || b == 'e' || b == 'i' || b == 'o' || b == 'u' {
+        vowels += 1;
+    }
+
+    let mut doubles = false;
+    let mut no_evil_substrings = true;
+
+    for c in iter {
+        a = b;
+        b = c;
+
+        if a == b {
+            doubles = true;
+        }
+
+        if (a, b) == ('a', 'b')
+            || (a, b) == ('c', 'd')
+            || (a, b) == ('p', 'q')
+            || (a, b) == ('x', 'y')
+        {
+            no_evil_substrings = false;
+        }
+
+        if b == 'a' || b == 'e' || b == 'i' || b == 'o' || b == 'u' {
+            vowels += 1;
+        }
+    }
+
+    doubles && no_evil_substrings && vowels >= 3
+}
+
+fn solve_second(input: &str) -> usize {
+    let mut result = 0;
+
+    for s in input.lines() {
+        if is_nice2(s) {
+            result += 1;
+        }
+    }
+
+    result
+}
+
+fn is_nice2(line: &str) -> bool {
+    let mut iter = line.chars();
+    let (mut a, mut b, mut c) = (' ', iter.next().unwrap_or(' '), iter.next().unwrap_or(' '));
+    let mut double_pair = false;
+    let mut trio = false;
+    let mut visited_pairs = HashSet::new();
+
+    for d in iter {
+        a = b;
+        b = c;
+        c = d;
+
+        trio |= a == c;
+
+        visited_pairs.insert((a, b));
+
+        if let Some(_) = visited_pairs.get(&(b, c)) {
+            if !(a == b && b == c) {
+                double_pair = true;
+            }
+        }
+    }
+
+    double_pair && trio
+}
+
+fn main() {
+    println!("Hello, this is Patrick!");
+
+    let input_txt = include_str!("../input.txt");
+
+    let first_result = solve_first(input_txt);
+
+    println!("The number of nice strings is {}", first_result);
+
+    let second_result = solve_second(input_txt);
+
+    println!(
+        "The number of new and improved nice strings is {}",
+        second_result
+    );
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn aaa_is_nice() {
+        assert!(is_nice("aaa"));
+    }
+
+    #[test]
+    fn ugknbfddgicrmopn_is_nice() {
+        assert!(is_nice("ugknbfddgicrmopn"));
+    }
+
+    #[test]
+    fn jchzalrnumimnmhp_is_naughty() {
+        assert!(!is_nice("jchzalrnumimnmhp"));
+    }
+
+    #[test]
+    fn haegwjzuvuyypxyu_is_naughty() {
+        assert!(!is_nice("haegwjzuvuyypxyu"));
+    }
+
+    #[test]
+    fn dvszwmarrgswjxmb_is_naughty() {
+        assert!(!is_nice("dvszwmarrgswjxmb"));
+    }
+
+    #[test]
+    fn qjhvhtzxzqqjkmpb_is_nice2() {
+        assert!(is_nice2("qjhvhtzxzqqjkmpb"));
+    }
+
+    #[test]
+    fn xxyxx_is_nice2() {
+        assert!(is_nice2("xxyxx"));
+    }
+
+    #[test]
+    fn uurcxstgmygtbstg_is_naughty2() {
+        assert!(!is_nice2("uurcxstgmygtbstg"));
+    }
+
+    #[test]
+    fn ieodomkazucvgmuy_is_naughty2() {
+        assert!(!is_nice2("ieodomkazucvgmuy"));
+    }
+
+    #[test]
+    fn aaa_is_naughty2() {
+        assert!(!is_nice2("aaa"));
+    }
+}