You are playing the following Flip Game with your friend: Given a string that contains only these two characters:
+
and
-
, you and your friend take turns to flip two
consecutive
"++"
into
"--"
. The game ends when a person can no longer make a move and therefore the other person will be the winner.
Write a function to compute all possible states of the string after one valid move.
Example:
Input:
s = "++++"
Output:
[
"--++",
"+--+",
"++--"
]
Note:
If there is no valid move, return an empty list
[]
.