java 實現快速排序

public static int partition(int[] a, int f, int b) {
        int pivot = a[f];
        while (f < b) {
            while (f < b && a[b] >= pivot) {
                b--;
            }
            while (f < b && a[f] < pivot) {
                f++;
            }
            if (f < b) {
                int tmpB = a[b];
                a[b] = a[f];
                a[f] = tmpB;
            }
        }       
        return b;
    }

    public static void quickSort(int[] a, int f, int b) {
        if (f < b) {
            int division = partition(a, f, b);
            quickSort(a, f, division);
            quickSort(a, division + 1, b);
        }
    }