add day 14

day14/Cargo.lock

@@ -0,0 +1,32 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day14"
+version = "0.1.0"
+dependencies = [
+ "itertools",
+ "md5",
+]
+
+[[package]]
+name = "either"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "91622ff5e7162018101f2fea40d6ebf4a78bbe5a49736a2020649edf9693679e"
+
+[[package]]
+name = "itertools"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b4baf93f58d4425749ca49a51c50ebab072c5df6994d08fed93541c331481dc"
+dependencies = [
+ "either",
+]
+
+[[package]]
+name = "md5"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae960838283323069879657ca3de837e9f7bbb4c7bf6ea7f1b290d5e9476d2e0"

day14/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "day14"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+md5 = "0.8.0"
+itertools = "*"

day14/src/main.rs

@@ -0,0 +1,99 @@
+use std::collections::VecDeque;
+
+use itertools::Itertools;
+
+#[cfg(debug_assertions)]
+const INPUT: &str = "abc";
+#[cfg(not(debug_assertions))]
+const INPUT: &str = "ihaygndm";
+
+fn main() {
+    part_1();
+    part_2();
+}
+
+fn part_2() {
+    let mut next_hashes = VecDeque::new();
+
+    let mut idx = 0;
+    let mut found_key_counter = 0;
+
+    loop {
+        while next_hashes.len() < 1_000 {
+            next_hashes.push_back(calculate_hash_repeated(INPUT, idx, 2016));
+            idx += 1;
+        }
+
+        let this_hash = next_hashes.pop_front().unwrap();
+
+        if let Some(found_char) = find_triple_char(&this_hash)
+            && next_hashes
+                .iter()
+                .any(|s| contains_quintuple(s.as_str(), found_char))
+        {
+            found_key_counter += 1;
+            if found_key_counter == 64 {
+                println!("{}", idx - 1000);
+                break;
+            }
+        }
+    }
+}
+
+fn part_1() {
+    let mut next_hashes = VecDeque::new();
+
+    let mut idx = 0;
+    let mut found_key_counter = 0;
+
+    loop {
+        while next_hashes.len() < 1_000 {
+            next_hashes.push_back(calculate_hash(INPUT, idx));
+            idx += 1;
+        }
+
+        let this_hash = next_hashes.pop_front().unwrap();
+
+        if let Some(found_char) = find_triple_char(&this_hash)
+            && next_hashes
+                .iter()
+                .any(|s| contains_quintuple(s.as_str(), found_char))
+        {
+            found_key_counter += 1;
+            if found_key_counter == 64 {
+                println!("{}", idx - 1000);
+                break;
+            }
+        }
+    }
+}
+
+fn calculate_hash(s: &str, idx: usize) -> String {
+    format!("{:x}", md5::compute(format!("{s}{idx}")))
+}
+
+fn calculate_hash_repeated(s: &str, idx: usize, count: usize) -> String {
+    let mut hash = calculate_hash(s, idx);
+
+    for _ in 0..count {
+        hash = format!("{:x}", md5::compute(hash));
+    }
+
+    hash
+}
+
+fn find_triple_char(s: &str) -> Option<char> {
+    s.chars()
+        .tuple_windows()
+        .filter(|(a, b, c)| a == b && b == c)
+        .map(|(c, _, _)| c)
+        .next()
+}
+
+fn contains_quintuple(s: &str, value: char) -> bool {
+    s.chars().tuple_windows().any(|(a, b, c, d, e)| {
+        let head = a;
+        [b, c, d, e].into_iter().all(|ch| head == ch) // all items are identical
+            && head == value
+    })
+}