Day6 but faaaast

src/bin/day6.rs

@@ -1,9 +1,30 @@
-use itertools::Itertools;
-use std::collections::HashSet;
 use std::error::Error;
 use std::fs::File;
 use std::io::{self, BufRead};
-use std::vec::Vec;
+
+fn find_sequence(line: &str, len: usize) -> usize {
+    let mut answer = 0;
+
+    for i in 0..line.len() - len {
+        let mut set1 = 0u32;
+        let mut repeated = false;
+        for c in line[i..i + len].chars() {
+            let bit = 1 << (c as u32 - 'a' as u32);
+            if bit & set1 == 0 {
+                set1 |= bit;
+            } else {
+                repeated = true;
+                break;
+            }
+        }
+        if !repeated {
+            answer = i + len;
+            break;
+        }
+    }
+
+    return answer;
+}
 
 fn main() -> Result<(), Box<dyn Error>> {
     let file = File::open("inputs/day6.txt")?;
@@ -14,28 +35,10 @@ fn main() -> Result<(), Box<dyn Error>> {
         .unwrap()
         .to_owned();
 
-    let mut answer1 = 0;
-
-    for i in 0..line.len() - 4 {
-        let set: HashSet<char> = line[i..i + 4].chars().collect();
-        if set.len() == 4 {
-            answer1 = i + 4;
-            break;
-        }
-    }
-
+    let answer1 = find_sequence(&line, 4);
     println!("Answer Part1: {}", answer1);
 
-    let mut answer2 = 0;
-
-    for i in 0..line.len() - 14 {
-        let set: HashSet<char> = line[i..i + 14].chars().collect();
-        if set.len() == 14 {
-            answer2 = i + 14;
-            break;
-        }
-    }
-
+    let answer2 = find_sequence(&line, 14);
     println!("Answer Part2: {}", answer2);
 
     Ok(())