Introduction

In this blog post, we will explore how to solve the LeetCode problem "1750" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

Given a string s consisting only of characters 'a', 'b', and 'c'. You are asked to apply the following algorithm on the string any number of times: Pick a non-empty prefix from the string s where all the characters in the prefix are equal. Pick a non-empty suffix from the string s where all the characters in this suffix are equal. The prefix and the suffix should not intersect at any index. The characters from the prefix and suffix must be the same. Delete both the prefix and the suffix. Return the minimum length of s after performing the above operation any number of times (possibly zero times). Example 1: Input: s = "ca" Output: 2 Explanation: You can't remove any characters, so the string stays as is. Example 2: Input: s = "cabaabac" Output: 0 Explanation: An optimal sequence of operations is: - Take prefix = "c" and suffix = "c" and remove them, s = "abaaba". - Take prefix = "a" and suffix = "a" and remove them, s = "baab". - Take prefix = "b" and suffix = "b" and remove them, s = "aa". - Take prefix = "a" and suffix = "a" and remove them, s = "". Example 3: Input: s = "aabccabba" Output: 3 Explanation: An optimal sequence of operations is: - Take prefix = "aa" and suffix = "a" and remove them, s = "bccabb". - Take prefix = "b" and suffix = "bb" and remove them, s = "cca". Constraints: 1 <= s.length <= 105 s only consists of characters 'a', 'b', and 'c'.

Explanation

Here's the approach to solve this problem efficiently:

• Identify Matching Prefix and Suffix: Iterate through the string from both ends, identifying the longest prefix and suffix that have the same character.
• Shrink the String: If a matching prefix and suffix are found, remove them, effectively shrinking the string.

• Repeat: Continue this process until no more matching prefix and suffix can be found. The remaining length of the string is the answer.

• Runtime Complexity: O(n), where n is the length of the string. Storage Complexity: O(1).

Code

    def minimum_length(s: str) -> int:
    """
    Given a string s consisting only of characters 'a', 'b', and 'c'.
    You are asked to apply the following algorithm on the string any number of times:
    Pick a non-empty prefix from the string s where all the characters in the prefix are equal.
    Pick a non-empty suffix from the string s where all the characters in this suffix are equal.
    The prefix and the suffix should not intersect at any index.
    The characters from the prefix and suffix must be the same.
    Delete both the prefix and the suffix.
    Return the minimum length of s after performing the above operation any number of times (possibly zero times).
    """
    left = 0
    right = len(s) - 1

    while left < right and s[left] == s[right]:
        char = s[left]

        while left <= right and s[left] == char:
            left += 1
        while left <= right and s[right] == char:
            right -= 1

    return max(0, right - left + 1)