Array
(
[0] => Array
(
[0] => m
[1] => n
)
[1] => Array
(
[0] => a
[1] => e
)
[2] => Array
(
[0] => he
[1] => hu
[2] => huo
)
[3] => Array
(
[0] => b
)
)
希望的结果
array(
[0] => m,a,he,b
[1] => m,e,he,b
[2] => m,a,hu,b
[3] => m,e,hu,b
[4] => m,a,huo,b
[5] => m,e,huo,b
[6] => n,a,he,b
[7] => n,e,he,b
[8] => n,a,hu,b
[9] => n,e,hu,b
[10] => n,a,huo,b
[11] => n,e,huo,b
)
m,a,he,b
....
....
这些值得顺序不能变
求解