[LeetCode] 86. Partition List java

    /**86. Partition List 
     * @param head
     * @param x
     * @return 比x小放左邊，>=x放在右邊
     */
    public ListNode partition(ListNode head, int x) {
        ListNode left = new ListNode(-1);
        ListNode right = new ListNode(-1);
        ListNode leftHead = left;
        ListNode rightHead = right;
        int count = 0;
        while (head != null) {
            if (head.val < x) {
                left.next = new ListNode(head.val);
                left = left.next;
            } else if (head.val >= x) {
                right.next = new ListNode(head.val);
                right = right.next;
            }
            head = head.next;
        }
        left.next = rightHead.next;
        return leftHead.next;
    }