[Data Sturcture] Quick sort

public class QuickSorter {

    // main
    public static void quickSort(int[] arr) {
        sort(arr, 0, arr.length - 1);
    }

    private static void sort(int[] arr, int low, int high) {
        if (low >= high) return;

        int mid = partition(arr, low, high); // divide
        sort(arr, low, mid - 1); // 0 ~ mid - 1
        sort(arr, mid, high); // mid ~ arr.length - 1
    }

    private static int partition(int[] arr, int low, int high) {
        
        int pivot = arr[(low + high) / 2];
        
        while (low <= high) {
            while (arr[low] < pivot) low++;
            while (arr[high] > pivot) high--;
            if (low <= high) {
                swap(arr, low, high);
                low++;
                high--;
            }
        }

        return low;
    }

    private static void swap(int[] arr, int i, int j) {
        int tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }
}