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 determine if the starting player can guarantee a win.
Example:
Input:s = "++++"Output: true Explanation: The starting player can guarantee a win by flipping the middle"++"to become"+--+".
Follow up:
Derive your algorithm's runtime complexity.