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 twoconsecutive"++"
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[]
.
class Solution {
public List<String> generatePossibleNextMoves(String s) {
List<String> ans = new ArrayList<>();
if (s == null || s.length() < 2) return ans;
for (int i = 0; i < s.length() - 1; i++){
if (i + 1 < s.length() && s.substring(i, i + 2).equals("++")){
ans.add(s.substring(0, i) + "--" + s.substring(i + 2));
}
}
return ans;
}
}