**求教一道题-所有list的所有word组合非递归

面了一下午脑子都不转了。。{:4_106:}连着搞了3个面试还都是三哥们。。
题目是这样的比如有一个arraylist of string arraylists {{“a","b","c"},{"d","e","f"},{"g","h","i"}}
要求输出所有可能的combination 结果大概是
{{"a","d","g"},{"a" ,"d", "h"}, {"a","d","i"},{"b","d","g",{"b","d","h"}..........}以此类推比如上面的情况最后应该是3*3*3个可能
一开始的list的数目不确定， 且规定不能使用递归来实现

现在暴力法感觉都卡住想不动了{:4_85:}还请地里大神们来点播一下小弟不胜感激{:4_107:}