Introduction

In this blog post, we will explore how to solve the LeetCode problem "3498" 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, calculate its reverse degree. The reverse degree is calculated as follows: For each character, multiply its position in the reversed alphabet ('a' = 26, 'b' = 25, ..., 'z' = 1) with its position in the string (1-indexed). Sum these products for all characters in the string. Return the reverse degree of s. Example 1: Input: s = "abc" Output: 148 Explanation: Letter Index in Reversed Alphabet Index in String Product 'a' 26 1 26 'b' 25 2 50 'c' 24 3 72 The reversed degree is 26 + 50 + 72 = 148. Example 2: Input: s = "zaza" Output: 160 Explanation: Letter Index in Reversed Alphabet Index in String Product 'z' 1 1 1 'a' 26 2 52 'z' 1 3 3 'a' 26 4 104 The reverse degree is 1 + 52 + 3 + 104 = 160. Constraints: 1 <= s.length <= 1000 s contains only lowercase English letters.

Explanation

Here's the approach, complexity, and code for calculating the reverse degree of a string:

• Iterate through the string: Process each character of the input string from left to right.
• Calculate the reversed alphabet position: Determine the reversed alphabet position of each character (a=26, b=25, ..., z=1). This can be efficiently done using the character's ASCII value.

• Accumulate the product: Multiply the reversed alphabet position by the character's position in the string (1-indexed) and add it to the running sum, which represents the reverse degree.

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

• Storage Complexity: O(1), as we only use a few constant extra variables.

Code

    def reverse_degree(s: str) -> int:
    """
    Calculates the reverse degree of a string.

    The reverse degree is calculated as follows:
    For each character, multiply its position in the reversed alphabet ('a' = 26, 'b' = 25, ..., 'z' = 1)
    with its position in the string (1-indexed).
    Sum these products for all characters in the string.

    Example:
    reverse_degree("abc") == 148
    reverse_degree("zaza") == 160
    """
    reverse_degree_sum = 0
    for i, char in enumerate(s):
        reversed_alphabet_position = ord('z') - ord(char) + 1
        reverse_degree_sum += reversed_alphabet_position * (i + 1)
    return reverse_degree_sum