Add solution for day 6

rust/src/bin/day06.rs

@@ -0,0 +1,54 @@
+use rust::util::read_input;
+use std::collections::{hash_map::RandomState, HashSet, VecDeque};
+
+fn part1(input: &str) -> usize {
+    let mut previous_three: VecDeque<char> = VecDeque::new();
+    for (i, c) in input.char_indices() {
+        if previous_three.len() < 3 {
+            previous_three.push_back(c);
+            continue;
+        }
+
+        let set: HashSet<&char, RandomState> = HashSet::from_iter(previous_three.iter());
+        if previous_three.contains(&c) || set.len() < 3 {
+            previous_three.pop_front();
+            previous_three.push_back(c);
+            continue;
+        }
+
+        return i + 1;
+    }
+    0
+}
+
+fn part2(input: &str) -> usize {
+    let mut previous_three: VecDeque<char> = VecDeque::new();
+    for (i, c) in input.char_indices() {
+        if previous_three.len() < 13 {
+            previous_three.push_back(c);
+            continue;
+        }
+
+        let set: HashSet<&char, RandomState> = HashSet::from_iter(previous_three.iter());
+        if previous_three.contains(&c) || set.len() < 13 {
+            previous_three.pop_front();
+            previous_three.push_back(c);
+            continue;
+        }
+
+        return i + 1;
+    }
+    0
+}
+
+fn main() {
+    let test_input = read_input("Day06_test").expect("Failed to open test input");
+    let test_input_first = test_input.first().expect("Received empty input");
+    assert_eq!(7, part1(&test_input_first));
+    assert_eq!(19, part2(&test_input_first));
+
+    let input = read_input("Day06").expect("Failed to open input");
+    let input_first = input.first().expect("Received empty input");
+    println!("{:?}", part1(&input_first));
+    println!("{:?}", part2(&input_first));
+}