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 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 [].

    翻译文：

    你正在和你的朋友玩下面的翻转游戏:给定一个字符串，它只包含这两个字符:+和-，你和你的朋友轮流把两个连续的“++”翻转成“——”。游戏结束时，一个人不能再采取行动，因此另一个人将是赢家。
    写一个函数来计算一个有效移动后字符串的所有可能状态。

    ``

    1. public class Solution {
    2.     public List<String> generatePossibleNextMoves(String s) {
    3.         //  哈哈哈， 没看懂
    4.         List<Character> list = new ArrayList<>();
    6.         Char []str = s.toCharArray();
    8.         for(int i = 1; i < s.length(); i++){
    9.                 if(str[i] == '+' && str[i - 1] == '+'){
    10.                        str[i] = '-';
    11.                     str[i - 1] = '-';
    12.                     list.add(String.valueOF(str));
    13.                     str[i] = '+';
    14.                     str[i - 1] = '+';
    15.                }
    16.         }
    17.         return list;
    19.     }
    20. }

    ``