public class QuickSort {
    /**
     * 
     * @param numArr Number array to sort
     * @param i Lower index of number array to sort
     * @param k Upper index of number array to sort
     * @return
     */
    public static int partition(int[] numArr, int i, int k) {
        int midPoint = i + (k - i) / 2; // why not k / 2 ?
        int pivot = numArr[midPoint];
        boolean done = false;

        // Lower
        int l = i;
        //Higher
        int h = k;

        while(!done) {
            while(numArr[l] < pivot) {
                l++;
            }
            while(pivot < numArr[h]) {
                h--;
            }

            if(l >= h) {
                done = true;
            }
            else {
                int temp = numArr[l];
                numArr[l] = numArr[h];
                numArr[h] = temp;
                l++;
                h--;
            }
        }
        PrintArray.printIntArray(numArr);
        return h;
    }

    public static void quickSort(int[] numArr, int i, int k) {
        if(i >= k) {
            return;
        }

        int j = partition(numArr, i, k);

        quickSort(numArr, i, j);
        quickSort(numArr, j + 1, k);
    }

    public static void main (String[] args) {
        int[] nums = {5, 6, 2, 10, 4};

        System.out.print("Unsorted array : ");
        PrintArray.printIntArray(nums);

        quickSort(nums, 0, nums.length - 1);

        System.out.print("Sorted array : ");
        PrintArray.printIntArray(nums);
    }
}