判断栈的出栈顺序合法性

    public static boolean stackOrder(int[] nums){
        int[] origin=new int[]{1,2,3,4,5,6,7,8,9};
        //假定出栈序列也是1-9的数列
        Deque<Integer> q=new ArrayDeque<>();
        int index=0,i=0;
        for (i=0;i<nums.length;){
            if(!q.isEmpty()&& nums[i]==q.getLast()){
                q.pollLast();
                i++;
            }
            else {
                if(index<9) {
                    q.addLast(origin[index++]);
                }
                else break;
            }
        }
        return i==nums.length?true:false;
    }