day 6

d6/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "d6"
+version = "0.1.0"

d6/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "d6"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

d6/src/main.rs

@@ -0,0 +1,55 @@
+use std::{fs::read_to_string, io::Result};
+
+fn all_diff<T: PartialEq>(list: &[T]) -> bool {
+    for i in 0..list.len() {
+        let a = &list[i];
+        for j in 0..i {
+            let b = &list[j];
+            if a == b {
+                return false;
+            }
+        }
+    }
+    true
+}
+
+fn main() -> Result<()> {
+    let mut p1_ring_buf = [None; 4];
+    let mut p1_pos = 0;
+    let mut p2_ring_buf = [None; 14];
+    let mut p2_pos = 0;
+
+    let mut p1_result = 0;
+    let mut p2_result = 0;
+
+    for (i, c) in read_to_string("input.txt")?.chars().enumerate() {
+        p1_ring_buf[p1_pos] = Some(c);
+        p1_pos += 1;
+        if p1_pos == p1_ring_buf.len() {
+            p1_pos = 0
+        }
+
+        p2_ring_buf[p2_pos] = Some(c);
+        p2_pos += 1;
+        if p2_pos == p2_ring_buf.len() {
+            p2_pos = 0
+        }
+
+        if p1_result == 0 {
+            if i >= p1_ring_buf.len() && all_diff(&p1_ring_buf) {
+                p1_result = i + 1;
+            }
+        }
+
+        if p2_result == 0 {
+            if i >= p2_ring_buf.len() && all_diff(&p2_ring_buf) {
+                p2_result = i + 1;
+            }
+        }
+    }
+
+    println!("Part 1: {}", p1_result);
+    println!("Part 2: {}", p2_result);
+
+    Ok(())
+}