Merge pull request #1 from johannes67890/quicksort

Quicksort

Author: johannes67890

README.md

@@ -1,2 +1,23 @@
 # Sorting-algorithm
+
 Sorting algorithms in Rust.
+
+## Table of Contents
+
+- [Install](#install)
+- [Usage](#usage)
+- [Showcase](#showcase)
+- [Benchmarks](#benchmarks)
+- [Instructions](#instructions)
+- [Supported Curves](#supported-curves)
+- [3rd party libraries used](#supported-curves)
+
+## Install
+
+## Usage
+
+## Benchmarks
+
+## Showcase
+
+## Supported Algoritms

benches/sort_benchmark.rs

@@ -1,11 +1,12 @@
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
 use sorting_algorithm::bubblesort;
+use sorting_algorithm::quicksort;
 
 fn sort_arrays_benchmark(c: &mut Criterion) {
     let mut arr = black_box([-2,-7,2,10,20,9]);
 
-    c.bench_function("Bubblesort", |b| b.iter(|| bubblesort(&mut arr)));
-
+    c.bench_function("Bubble Sort", |b| b.iter(|| bubblesort(&mut arr)));
+    c.bench_function("Quick Sort", |b| b.iter(|| quicksort(&mut arr)));
 }
 
 criterion_group!(benches, sort_arrays_benchmark);

src/lib.rs

@@ -4,6 +4,12 @@ mod quciksort;
 pub use bubblesort::bubblesort;
 pub use quciksort::quicksort;
 
+// pub fn generate_random_array(salt: i8, range: i32) -> &[i32]{
+//     let mut arr = [];
+//     &arr
+// }
+
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -15,8 +21,8 @@ mod tests {
     }
     #[test]
     fn test_quick_sort() {
-        let mut array = [10, 7, 8, 9, 1, 5];
-        let sorted = quicksort(&mut array);
-        assert_eq!(sorted, &[1, 5, 7, 8, 9, 10]);
+        let mut arr = [6, 2, 4, 1, 9, -2, 5];
+        quicksort(&mut arr);
+        assert_eq!(arr, [-2, 1, 2, 4, 5, 6, 9]);
     }
 }

src/quciksort.rs

@@ -1,35 +1,62 @@
-pub fn quicksort(array: &mut [i32]) -> &[i32] {
-    let low: isize = 0;
-    let high: isize = (array.len() - 1) as isize;
+
+/// # Quicksort
+/// 
+/// The Quicksort algoritm is a Divide and Conquer algorithm. 
+/// Quicksort selects a `pivot` element, and takes the other elements smaller or equal on one side and bigger on the other side.
+/// 
+/// # Ilustration 
+/// `arr = [ 8, 5, 9, 2, 7 ]` (pivot is the last element, in this case 7).
+/// 
+///                <-- `less or equal`      `bigger than` -->
+/// 
+///                              [ 8, 5, 9, 2, 7 ]
+///                                      |
+///                      / ------------- 7 ----------------\ 
+///                  [ 5, 2 ]                            [ 8, 9 ]
+///                      |                                  |
+///               [ ] -- 2 -- [5]                    [8] -- 9 -- [ ]   
+///                      |                                  |            <---- `Now we join them back together`
+///                      \-----    [ 2, 5, 7, 8, 9 ]   ---- /
+///                                  (Sorted array)
+///          
+pub fn quicksort<T: Ord>(array: &mut [T]) { // Takes mut array of type 'T'.
+    let low: isize = 0; // Index '0' of array
+    let high: isize = (array.len() - 1) as isize; // Highest index of array
 
-   sort(array, low, high);
+    sort(array, low, high);
 
+}
 
-    fn sort(array: &mut [i32], low: isize, high: isize) -> &[i32]{
-        if low < high {
-            let pi: isize = temp(array, low, high);
 
-            sort(array, low, pi - 1);
-            sort(array, (pi + 1) as isize, high);
-         }
-         array
-    }
+fn sort<T: Ord>(arr: &mut [T], low: isize, high: isize){
+    if low < high {
+        let pivot_element: isize = temp(arr, low, high); // pivot element (always the element of the highest index, in the whole or sub array)
 
-    fn temp(array: &mut [i32], low: isize, high: isize) -> isize {
-        let temp = array[high as usize];
-        let mut i = low - 1; 
-
-        for j in 0..high {
-            if array[j as usize] < temp {
+        sort(arr, low, pivot_element - 1); // Before pi
+        sort(arr, pivot_element + 1, high); // After pi
+    }
+    
+    fn temp<T: Ord>(arr: &mut [T], low: isize, high: isize) -> isize {
+    let pivot = high as usize; // Pivot element
+    let mut i = low - 1; 
+    let mut j = high;
+
+    loop {
+            i += 1;
+            while arr[i as usize] < arr[pivot] {
                 i += 1;
-
-                array.swap(i as usize, j as usize);
-
+            }
+            j -= 1;
+            while j >= 0 && arr[j as usize] > arr[pivot] {
+                j -= 1;
+            }  
+            if i >= j { // If current element is smaller than pivot element.
+                break;
+            } else {
+                arr.swap(i as usize, j as usize);
             }
         }
-       array.swap((i + 1) as usize, high as usize);
-       i + 1
+        arr.swap(i as usize, pivot as usize);
+        i
     }
-
-    array
 }