modified the function to take slices as input and return a vector without the need to create and manipulate additional Vec instances.

src/sorting/merge_sort.rs

@@ -7,32 +7,32 @@ pub fn merge_sort<T: Ord + Copy>(array: &[T]) -> Vec<T> {
  if array.len() < 2 {
  return array.to_vec();
  }
- // Get the middle element of the array.
  let middle = array.len() / 2;
- // Divide the array into left and right halves.
- let mut left = merge_sort(&array[..middle]);
- let mut right = merge_sort(&array[middle..]);
- // Call merge function using parameters as both left array and right array.
- merge(&mut left, &mut right)
+ let left = merge_sort(&array[..middle]);
+ let right = merge_sort(&array[middle..]);
+ merge(&left, &right)
 }
 
-fn merge<T: Ord + Copy>(left: &mut Vec<T>, right: &mut Vec<T>) -> Vec<T> {
- let mut result = Vec::new();
-
- for _ in 0..left.len() + right.len() {
- if left.is_empty() {
-  result.append(right);
-  break;
- } else if right.is_empty() {
-  result.append(left);
-  break;
- } else if left[0] <= right[0] {
- result.push(left.remove(0));
+fn merge<T: Ord + Copy>(left: &[T], right: &[T]) -> Vec<T> {
+ let mut result = Vec::with_capacity(left.len() + right.len());
+ let mut left_iter = left.iter();
+ let mut right_iter = right.iter();
+
+ let mut left_next = left_iter.next();
+ let mut right_next = right_iter.next();
+
+ while let (Some(left_val), Some(right_val)) = (left_next, right_next) {
+ if left_val <= right_val {
+  result.push(*left_val);
+ left_next = left_iter.next();
  } else {
- result.push(right.remove(0));
+ result.push(*right_val);
+ right_next = right_iter.next();
  }
  }
 
+ result.extend(left_next);
+ result.extend(right_next);
  result
 }