add slice window variants for day 1

because it's based on slices, it's more performant than the tuple
variant, but it's more error prone, because the bounds checking happens
at runtime instead.

src/day_01.rs

@@ -32,6 +32,17 @@ pub fn count_increases_tuple_windows(input: &[usize]) -> usize {
     count
 }
 
+#[aoc(day1, part1, slice_windows)]
+pub fn count_increases_slice_windows(input: &[usize]) -> usize {
+    let mut count = 0;
+    for window in input.windows(2) {
+        if window[0] < window[1] {
+            count += 1;
+        }
+    }
+    count
+}
+
 #[aoc(day1, part2)]
 pub fn count_sliding_increases_indexed(input: &[usize]) -> usize {
     let mut count = 0;
@@ -53,3 +64,14 @@ pub fn count_sliding_increases_tuple_windows(input: &[usize]) -> usize {
     }
     count
 }
+
+#[aoc(day1, part2, slice_windows)]
+pub fn count_sliding_increases_slice_windows(input: &[usize]) -> usize {
+    let mut count = 0;
+    for w in input.windows(4) {
+        if w[0] + w[1] + w[2] < w[1] + w[2] + w[3] {
+            count += 1;
+        }
+    }
+    count
+}