September 2017 Update

Task/Sorting-algorithms-Quicksort/Rust/sorting-algorithms-quicksort.rust

@@ -1,46 +1,39 @@
-// Type alias for function that returns true if arguments should be swapped
-type OrderFunc<T> = Fn(&T, &T) -> bool;
-
 fn main() {
-    // Sort numbers
+    println!("Sort numbers in descending order");
     let mut numbers = [4, 65, 2, -31, 0, 99, 2, 83, 782, 1];
     println!("Before: {:?}", numbers);
 
-    quick_sort(&mut numbers, &is_less);
-    println!("After: {:?}", numbers);
+    quick_sort(&mut numbers, &|x,y| x > y);
+    println!("After:  {:?}\n", numbers);
 
-    // Sort strings
+    println!("Sort strings alphabetically");
     let mut strings = ["beach", "hotel", "airplane", "car", "house", "art"];
     println!("Before: {:?}", strings);
 
-    quick_sort(&mut strings, &is_less);
-    println!("After: {:?}", strings);
+    quick_sort(&mut strings, &|x,y| x < y);
+    println!("After:  {:?}\n", strings);
+
+    println!("Sort strings by length");
+    println!("Before: {:?}", strings);
+
+    quick_sort(&mut strings, &|x,y| x.len() < y.len());
+    println!("After:  {:?}", strings);
 }
 
-
-// Example OrderFunc which is used to order items from least to greatest
-#[inline(always)]
-fn is_less<T: Ord>(x: &T, y: &T) -> bool {
-    x < y
-}
-
-fn quick_sort<T>(v: &mut [T], f: &OrderFunc<T>) {
-
+fn quick_sort<T,F>(v: &mut [T], f: &F)
+    where F: Fn(&T,&T) -> bool
+{
     let len = v.len();
-    if len < 2 {
-        return;
+    if len >= 2 {
+        let pivot_index = partition(v, f);
+        quick_sort(&mut v[0..pivot_index], f);
+        quick_sort(&mut v[pivot_index + 1..len], f);
     }
-
-    let pivot_index = partition(v, f);
-
-    // Sort the left side
-    quick_sort(&mut v[0..pivot_index], f);
-
-    // Sort the right side
-    quick_sort(&mut v[pivot_index + 1..len], f);
 }
 
-fn partition<T>(v: &mut [T], f: &OrderFunc<T>) -> usize {
+fn partition<T,F>(v: &mut [T], f: &F) -> usize
+    where F: Fn(&T,&T) -> bool
+{
     let len = v.len();
     let pivot_index = len / 2;