day02-2 super-fast

src/tasks/day02.rs

@@ -51,6 +51,30 @@ pub fn task2() {
     println!("Part 2: None found!");
 }
 
+pub fn task2_linear_asterisk() {
+    let input = utils::read_file("input/day02.txt");
+
+    let mut hashes =
+        HashSet::<String>::with_capacity(input.len() * input.lines().next().unwrap().len());
+
+    for line in input.lines() {
+        for i in 0..line.len() {
+            let string: String = line
+                .chars()
+                .enumerate()
+                .map(|(index, c)| if index == i { '*' } else { c })
+                .collect();
+
+            if hashes.contains(&string) {
+                println!("{} is double", string);
+                return;
+            } else {
+                hashes.insert(string);
+            }
+        }
+    }
+}
+
 pub fn task2_linear() {
     let input = utils::read_file("input/day02.txt");