给你一个字符串 target

Alice 将会使用一种特殊的键盘在她的电脑上输入 target,这个键盘 只有两个 按键:

注意,最初屏幕上是一个字符串 "",所以她 只能 按按键 1。

请你考虑按键次数 最少 的情况,按字符串出现顺序,返回 Alice 输入 target 时屏幕上出现的所有字符串列表。

 

示例 1:

输入: target = "abc"

输出: ["a","aa","ab","aba","abb","abc"]

解释:

Alice 按键的顺序如下:

示例 2:

输入: target = "he"

输出: ["a","b","c","d","e","f","g","h","ha","hb","hc","hd","he"]

 

提示: