How many flips HackerRank solution?

How Many Flips HackerRank Solution?

Introduction

HackerRank is a popular platform for coding challenges and competitions. One of the most common challenges on the platform is the "Flips" problem, which involves finding the minimum number of flips required to make a given string of characters into a palindrome. In this article, we will explore the HackerRank solution for the "Flips" problem and provide a step-by-step guide on how to solve it.

Problem Statement

Given a string of characters, find the minimum number of flips required to make it a palindrome. A palindrome is a string that reads the same backward as forward.

Example

Input: "aab"

Output: 0

Explanation: The string "aab" is already a palindrome, so no flips are required.

HackerRank Solution

The HackerRank solution for the "Flips" problem involves using a two-pointer technique to compare characters from the start and end of the string and move towards the center. Here is the solution in Python:

def min_flips(s):

    n = len(s)

    flips = 0

    for i in range(n // 2):

        if s[i] != s[n - i - 1]:

            flips += 1

    return flips

Explanation

We first calculate the length of the input string s.

We initialize a variable flips to 0, which will store the minimum number of flips required.

We iterate over the first half of the string using a for loop.

Inside the loop, we compare the characters at the current index i and the corresponding character at the end of the string n - i - 1. If they are different, we increment the flips variable by 1.

After the loop, we return the flips variable, which represents the minimum number of flips required.

Time Complexity

The time complexity of the HackerRank solution is O(n), where n is the length of the input string. This is because we are iterating over the first half of the string once.

Space Complexity

The space complexity of the HackerRank solution is O(1), which means it uses constant space. This is because we are not using any additional data structures that scale with the input size.

Example Use Cases

Here are some example use cases for the HackerRank solution:

print(min_flips("aab"))  # Output: 0

print(min_flips("abc"))  # Output: 1

print(min_flips("abca"))  # Output: 0

Conclusion

In conclusion, the HackerRank solution for the "Flips" problem is a simple and efficient algorithm that uses a two-pointer technique to compare characters from the start and end of the string and move towards the center. The solution has a time complexity of O(n) and a space complexity of O(1), making it suitable for large input sizes. With this solution, you can easily find the minimum number of flips required to make a given string of characters into a palindrome.

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