Flip Game — LeetCode 293 Python Solution

The problem

You are playing a Flip Game with your friend. You are given a string currentState that contains only '+' and '-'.

Example

Input

currentState = "++++"

Output

["--++","+--+","++--"]

Python solution

class Solution:
    def generatePossibleNextMoves(self, currentState: str) -> List[str]:
        s = list(currentState)
        ans = []
        for i, (a, b) in enumerate(pairwise(s)):
            if a == b == "+":
                s[i] = s[i + 1] = "-"
                ans.append("".join(s))
                s[i] = s[i + 1] = "+"
        return ans

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 293. Flip Game is filed here because the reference solution below belongs to the algorithm family this hub collects, even though its LeetCode tags point elsewhere.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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