### Question

Quicksort is a divide and conquer algorithm. It first divides a large list into two smaller sub-lists and then recursively sort the two sub-lists. If we want to sort an array without any extra space, Quicksort is a good option. On average, time complexity is O(n log(n)).

### Solution

This question is not easy. Practise more!

### Code

```
public static void quickSortRan(int[] arr, int low, int high) {
if (low >= high) {
return;
}
int pivot = arr[low + (high - low) / 2];
int left = low;
int right = high;
while (left < right) {
while (arr[left] < pivot) {
left++;
}
while (arr[right] > pivot) {
right--;
}
if (left <= right) {
int temp = arr[left];
arr[left] = arr[right];
arr[right] = temp;
left++;
right--;
}
}
quickSortRan(arr, low, right);
quickSortRan(arr, left, high);
}
```