Flip Game - Leetcode Solution

Flip Game is a simple problem on LeetCode that involves flipping consecutive two characters in a given string of + and - signs until there are no more consecutive two characters. The objective is to create all possible valid outcomes of the string after flipping.

Here’s a detailed solution to the Flip Game problem:

Step 1: Understanding the problem statement

Firstly, we need to understand the problem statement. The problem asks for all possible valid outcomes of a given string of + and – signs where we flip consecutive two characters until there are no more consecutive two characters left in the string.

Step 2: Create a function to solve the problem

To solve the problem, we can write a function named flip. The function takes a single argument, the given string of + and – signs. Inside the function, we initialize an empty list named res to store all possible valid outcomes of the string.

Step 3: Check if all consecutive two signs are – signs

We need to check if there are any consecutive two signs that are both – signs in the given string. We can use a for loop to iterate through the string from the start to the second-last character and check if the current and next characters are – signs. If they are, we can append the string with the flipped outcome to the result list.

Step 4: Return the result list

Finally, we return the result list of all possible valid outcomes of the given string.

Here’s the Python code snippet for the solution to the Flip Game problem:

def flip(s: str) -> List[str]:
    res = []
    for i in range(len(s) - 1):
        if s[i:i+2] == "--":
            res.append(s[:i] + "+" + s[i+2:])
    return res

In this code snippet, we first create an empty list named res to store all possible valid outcomes of the given string. We then use a for loop to iterate through the string from the start to the second-last character. Inside the for loop, we check if the current and next characters are both – signs by comparing a slice of two characters with “--”. If they are, we append the result list with the string with the two consecutive characters flipped with “+”. Finally, we return the result list.

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