Description
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 [].
Solution
Iteration, O(n), S(n)
class Solution {
public List<String> generatePossibleNextMoves(String s) {
List<String> res = new ArrayList<>();
if (s == null || s.length() < 2) {
return res;
}
char[] arr = s.toCharArray();
for (int i = 0; i < arr.length - 1; ++i) {
if (arr[i] == '+' && arr[i + 1] == '+') {
arr[i] = '-';
arr[i + 1] = '-';
res.add(new String(arr));
arr[i] = '+';
arr[i + 1] = '+';
}
}
return res;
}
}
