FlipGame.java

package com.fishercoder.solutions;

import java.util.ArrayList;
import java.util.List;
/**
 * 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:

 [
 "--++",
 "+--+",
 "++--"
 ]
 If there is no valid move, return an empty list [].*/
public class FlipGame {

    public List<String> generatePossibleNextMoves(String s) {
        
        List<String> result = new ArrayList<String>();
        for(int i = 1; i < s.length(); i++){
            if(s.charAt(i) == '+' && s.charAt(i-1) == '+'){
                result.add(s.substring(0, i-1) + "--" + s.substring(i+1));
            }
        }
        return result;
    
    }

}