feat(guide): added java implementation to quicksort (#36005)

* feat: added java implementation to quicksort

* fix: edited heading in quicksort

guide/english/algorithms/sorting-algorithms/quick-sort/index.md

@@ -185,6 +185,46 @@ function [pInd, unsorted] = partition(unsorted, low, high)
 
 end
 
+```
+### Implementation in Java
+
+```java
+public class Quicksort {
+
+  static void quickSort(int[] array, int p, int r) {
+      if (p < r) {
+          int q = partition(array, p, r);
+          quickSort(array, p, q - 1);
+          quickSort(array, q + 1, r);
+      }
+  }
+
+  static int partition(int[] array, int p, int r) {
+      // using the last element as the pivot
+      int pivot = array[r];
+      int i = p - 1;
+      for (int j = p; j <= r - 1; j++) {
+          if (array[j] <= pivot) {
+              i++;
+              int temp = array[i];
+              array[i] = array[j];
+              array[j] = temp;
+          }
+      }
+      int temp = array[i + 1];
+      array[i + 1] = array[r];
+      array[r] = temp;
+      return i + 1;
+  }
+
+    public static void main(String[] args) {
+      int [] array = {2,8,7,1,3,5,6,4};
+      quickSort(array, 0, 7);
+      for (int i : array)
+          System.out.print(i + " ");  
+   }
+}
+
 ```
 
 The space complexity of quick sort is `O(n)`. This is an improvement over other divide and conquer sorting algorithms, which take `O(nlong(n))` space. Quick sort achieves this by changing the order of elements within the given array. Compare this with the <a href='https://guide.freecodecamp.org/algorithms/sorting-algorithms/merge-sort' target='_blank' rel='nofollow'>merge sort</a> algorithm which creates 2 arrays, each length `n/2`, in each function call.
@@ -209,4 +249,3 @@ The space complexity of quick sort is O(n). This is an improvement over other di
 - <a href='https://www.youtube.com/watch?v=SLauY6PpjW4' target='_blank' rel='nofollow'>Youtube: Gayle Laakmann McDowell (author of Cracking The Coding Interview) explains the basics of quicksort and show some implementations</a>
 
 - <a href='https://www.youtube.com/watch?v=COk73cpQbFQ' target='_blank' rel='nofollow'>Quick Sort - MyCodeSchool</a>
-