Flip Game - Problem
You are playing a Flip Game with your friend. You are given a string currentState that contains only '+' and '-' characters.
You and your friend take turns to flip two consecutive "+" characters into "--". The game ends when a person can no longer make a move, and therefore the other person will be the winner.
Return all possible states of the string currentState after one valid move. You may return the answer in any order. If there is no valid move, return an empty list.
Input & Output
Example 1 — Single ++ Pair
$
Input:
currentState = "+--++"
›
Output:
["+----"]
💡 Note:
Only one ++ pair exists at positions 3-4, flipping it gives "+----"
Example 2 — Multiple ++ Pairs
$
Input:
currentState = "++--++"
›
Output:
["----++", "++----"]
💡 Note:
Two ++ pairs: positions 0-1 and 4-5. Flipping first gives "----++", flipping second gives "++----"
Example 3 — No Valid Moves
$
Input:
currentState = "+-+-"
›
Output:
[]
💡 Note:
No consecutive ++ pairs exist, so no valid moves possible
Constraints
- 1 ≤ currentState.length ≤ 500
- currentState[i] is either '+' or '-'
Visualization
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Explanation
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