d6p2

day6/src/main.rs

@@ -1,25 +1,24 @@
 use std::env;
 use std::fs::File;
 use std::io::{BufReader, Read};
+use std::collections::{VecDeque, HashSet};
 
 fn main() {
     let file = File::open(&env::args().nth(1).unwrap()).unwrap();
     let reader = BufReader::new(file);
 
-    let (mut x1, mut x2, mut x3) = (0, 0, 0);
+    let mut prevs: VecDeque<u8> = VecDeque::new();
     let mut i = 0;
     for byte in reader.bytes() {
         i += 1;
-        let c = byte.unwrap();
-        if c != x1 && c != x2 && c != x3
-                && x1 != x2 && x1 != x3 && x2 != x3
-                && x1 != 0 {
+        prevs.push_back(byte.unwrap());
+        if prevs.len() > 14 {
+            prevs.pop_front();
+        }
+        let set: HashSet<u8> = HashSet::from_iter(prevs.iter().cloned());
+        if set.len() == 14 {
             println!("{}", i);
             break;
-        } else {
-            x1 = x2;
-            x2 = x3;
-            x3 = c;
         }
     }
 }

day6/src/main1.rs

@@ -0,0 +1,26 @@
+use std::env;
+use std::fs::File;
+use std::io::{BufReader, Read};
+
+fn main() {
+    let file = File::open(&env::args().nth(1).unwrap()).unwrap();
+    let reader = BufReader::new(file);
+
+    let (mut x1, mut x2, mut x3) = (0, 0, 0);
+    let mut i = 0;
+    for byte in reader.bytes() {
+        i += 1;
+        let c = byte.unwrap();
+        if c != x1 && c != x2 && c != x3
+                && x1 != x2 && x1 != x3 && x2 != x3
+                && x1 != 0 {
+            println!("{}", i);
+            break;
+        } else {
+            x1 = x2;
+            x2 = x3;
+            x3 = c;
+        }
+    }
+}
+