June 2018 Update

Task/Sorting-algorithms-Pancake-sort/Rust/sorting-algorithms-pancake-sort.rust

@@ -0,0 +1,42 @@
+fn pancake_sort<T: Ord>(v: &mut [T]) {
+    let len = v.len();
+    // trivial case -- no flips
+    if len < 2 {
+        return;
+    }
+    for i in (0..len).rev() {
+        // find index of the maximum element within `v[0..i]` (inclusive)
+        let max_index = v.iter()
+            .take(i + 1)
+            .enumerate()
+            .max_by_key(|&(_, elem)| elem)
+            .map(|(idx, _)| idx)
+            // safe because we already checked if `v` is empty
+            .unwrap();
+        // if `max_index` is not where it's supposed to be
+        // do two flips to move it to `i`
+        if max_index != i {
+            flip(v, max_index);
+            flip(v, i);
+        }
+    }
+}
+
+// function to flip a section of a mutable collection from 0..num (inclusive)
+fn flip<E: PartialOrd>(v: &mut [E], num: usize) {
+    v[0..num + 1].reverse();
+}
+
+fn main() {
+    // Sort numbers
+    let mut numbers = [4, 65, 2, -31, 0, 99, 2, 83, 782, 1];
+    println!("Before: {:?}", numbers);
+    pancake_sort(&mut numbers);
+    println!("After: {:?}", numbers);
+
+    // Sort strings
+    let mut strings = ["beach", "hotel", "airplane", "car", "house", "art"];
+    println!("Before: {:?}", strings);
+    pancake_sort(&mut strings);
+    println!("After: {:?}", strings);
+}