public class Quick {

    private static void exchange(int[] a, int i, int j) {
        int temp = a[i];
        a[i] = a[j];
        a[j] = temp;
    }

    private static int partion(int[] a, int p, int r) {
        int x = a[r];
        int i = p-1;

        for (int j = p; j < r; j++) {
            if (a[j] <= x) {
                i = i + 1;
        		int temp = a[i];
        		a[i] = a[j];
        		a[j] = temp;
            }
        }
        int temp = a[i+1];
        a[i+1] = a[r];
        a[r] = temp;
        return i+1;
    }

    private static void quickSort(int[] a, int p, int r) {
        if (p < r) {
            int q = partion(a, p, r);
            quickSort(a, p, q-1);
            quickSort(a, q+1, r);
        }
    }

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

}