# Question

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

```
class Solution(object):
def generatePossibleNextMoves(self, s):
"""
:type s: str
:rtype: List[str]
"""
if len(s) <= 1:
return []
res = []
for i in range(1, len(s)):
if s[i] == s[i - 1] == '+':
res.append(s[:i-1] + '--' + s[i+1:])
return res
```