Introduction

In this blog post, we will explore how to solve the LeetCode problem "1422" 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 of zeros and ones, return the maximum score after splitting the string into two non-empty substrings (i.e. left substring and right substring). The score after splitting a string is the number of zeros in the left substring plus the number of ones in the right substring. Example 1: Input: s = "011101" Output: 5 Explanation: All possible ways of splitting s into two non-empty substrings are: left = "0" and right = "11101", score = 1 + 4 = 5 left = "01" and right = "1101", score = 1 + 3 = 4 left = "011" and right = "101", score = 1 + 2 = 3 left = "0111" and right = "01", score = 1 + 1 = 2 left = "01110" and right = "1", score = 2 + 1 = 3 Example 2: Input: s = "00111" Output: 5 Explanation: When left = "00" and right = "111", we get the maximum score = 2 + 3 = 5 Example 3: Input: s = "1111" Output: 3 Constraints: 2 <= s.length <= 500 The string s consists of characters '0' and '1' only.

Explanation

Here's an efficient solution to the problem, along with a breakdown of the approach and complexity:

• Approach:

  • Calculate the total number of ones in the string. This will be used to efficiently compute the number of ones in the right substring.
  • Iterate through all possible split positions (excluding the last character).
  • For each split, calculate the score by counting zeros in the left substring and ones in the right substring (derived from the total ones calculated earlier). Keep track of the maximum score found so far.

• Complexity:

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

Code

    def max_score_after_split(s: str) -> int:
    """
    Calculates the maximum score after splitting a string of zeros and ones into two non-empty substrings.

    Args:
        s: The input string consisting of '0' and '1'.

    Returns:
        The maximum score achievable after splitting the string.
    """
    total_ones = s.count('1')
    max_score = 0
    left_zeros = 0
    right_ones = total_ones

    for i in range(len(s) - 1):
        if s[i] == '0':
            left_zeros += 1
        else:
            right_ones -= 1  # or right_ones = total_ones - (i + 1 - left_zeros)

        max_score = max(max_score, left_zeros + right_ones)

    return max_score