private static void quickSort(int[] arr, int first, int last) { if (first > last) return; int i = first; int j = last; int mid = first + (last - first) / 2; swap(arr, first, mid); int pivot = first; while(i < j) { while(i arr[pivot]) j--; if (i < j) { swap(arr, i, j); } } swap(arr, pivot, j); quickSort(arr, first, j - 1); quickSort(arr, j + 1, last); } private static void swap(int[] arr, int i, ..