Flip Game

Source

• leetcode: 293

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.

For example, given s = "++++", after one move, it may become one of the following
states:

[
  "--++",
  "+--+",
  "++--"
]

Java

public List<String> generatePossibleNextMoves(String s) {

    List<String> list = new ArrayList<String>();

    for (int i = 1; i < s.length(); i++) {
        if (s.charAt(i) == '+' && s.charAt(i - 1) == '+') {
            list.add(s.substring(0, i - 1) + "--" + s.substring(i + 1, s.length()));
        }
    }

    return list;

}