Introduction

In this blog post, we will explore how to solve the LeetCode problem "389" 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

You are given two strings s and t. String t is generated by random shuffling string s and then add one more letter at a random position. Return the letter that was added to t. Example 1: Input: s = "abcd", t = "abcde" Output: "e" Explanation: 'e' is the letter that was added. Example 2: Input: s = "", t = "y" Output: "y" Constraints: 0 <= s.length <= 1000 t.length == s.length + 1 s and t consist of lowercase English letters.

Explanation

Here's the breakdown of the approach, complexity, and the Python code:

• Approach:

  • Calculate the sum of ASCII values of characters in string s.
  • Calculate the sum of ASCII values of characters in string t.
  • The difference between the two sums will be the ASCII value of the added character. Convert it back to a character.

• Complexity:

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

Code

    def findTheDifference(s: str, t: str) -> str:
    """
    Finds the letter that was added to t.

    Args:
        s: The original string.
        t: The shuffled string with one added letter.

    Returns:
        The added letter.
    """
    s_sum = 0
    t_sum = 0

    for char in s:
        s_sum += ord(char)

    for char in t:
        t_sum += ord(char)

    return chr(t_sum - s_sum)