y2015d10

y2015/src/bin/d10.rs

@@ -0,0 +1,14 @@
+use y2015::days::d10;
+
+fn main() {
+    part1();
+    part2();
+}
+
+fn part1() {
+    println!("{}", d10::process_part1("1321131112"));
+}
+
+fn part2() {
+    println!("{}", d10::process_part2("1321131112"));
+}

y2015/src/days/d10.rs

@@ -0,0 +1,57 @@
+pub fn process_part1(input: &str) -> u32 {
+    let mut number = input.to_string();
+    for _ in 0..40 {
+        number = look_and_say(&number);
+    }
+    number.len() as u32
+}
+
+pub fn process_part2(input: &str) -> u32 {
+    let mut number = input.to_string();
+    for _ in 0..50 {
+        number = look_and_say(&number);
+    }
+    number.len() as u32
+}
+
+fn look_and_say(number: &str) -> String {
+    let mut new_number = String::new();
+    let mut last_char = 'x';
+    let mut char_counter = 1;
+    for (idx, char) in number.chars().enumerate() {
+        if char == last_char {
+            char_counter += 1;
+        } else {
+            if idx != 0 {
+                new_number.push_str(format!("{char_counter}").as_str());
+                new_number.push(last_char);
+            }
+            last_char = char;
+            char_counter = 1;
+        }
+        if idx == number.len() - 1 {
+            new_number.push_str(format!("{char_counter}").as_str());
+            new_number.push(char);
+        }
+    }
+    new_number
+}
+
+#[cfg(test)]
+mod tests_10 {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let result = look_and_say("1");
+        assert_eq!(result, "11".to_string());
+        let result = look_and_say("11");
+        assert_eq!(result, "21".to_string());
+        let result = look_and_say("21");
+        assert_eq!(result, "1211".to_string());
+        let result = look_and_say("1211");
+        assert_eq!(result, "111221".to_string());
+        let result = look_and_say("111221");
+        assert_eq!(result, "312211".to_string());
+    }
+}

y2015/src/days/mod.rs

@@ -1,4 +1,5 @@
 pub mod d1;
+pub mod d10;
 pub mod d2;
 pub mod d3;
 pub mod d4;