293. Flip Game

题目：

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.

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 [].

链接： http://leetcode.com/problems/flip-game/

3/7/2017

public class Solution {
    public List<String> generatePossibleNextMoves(String s) {
        StringBuilder sb = new StringBuilder(s);
        List<String> ret = new ArrayList<String>();
        boolean inPlus = false;

        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) == '+') {
                if (inPlus) {
                    sb.setCharAt(i - 1, '-');
                    sb.setCharAt(i, '-');
                    ret.add(sb.toString());
                    sb = new StringBuilder(s);                
                } else inPlus = true;
            } else inPlus = false;
        }
        return ret;
    }
}