Introduction

In this blog post, we will explore how to solve the LeetCode problem "14" 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

Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix, return an empty string "". Example 1: Input: strs = ["flower","flow","flight"] Output: "fl" Example 2: Input: strs = ["dog","racecar","car"] Output: "" Explanation: There is no common prefix among the input strings. Constraints: 1 <= strs.length <= 200 0 <= strs[i].length <= 200 strs[i] consists of only lowercase English letters if it is non-empty.

Explanation

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

• High-Level Approach:

  • Iterate through the characters of the first string in the array.
  • For each character, check if all other strings in the array have the same character at the same index.
  • If a mismatch is found, return the prefix found so far. If the loop completes without a mismatch, the first string is the longest common prefix.

• Complexity:

  • Runtime: O(S), where S is the sum of all characters in all strings. In the worst case, we iterate through all the characters of all strings.
  • Storage: O(1). We use constant extra space.

Code

    def longestCommonPrefix(strs):
    """
    Finds the longest common prefix string amongst an array of strings.

    Args:
        strs: A list of strings.

    Returns:
        The longest common prefix string, or an empty string if there is none.
    """

    if not strs:
        return ""

    prefix = ""
    first_str = strs[0]

    for i in range(len(first_str)):
        char = first_str[i]
        for j in range(1, len(strs)):
            if i >= len(strs[j]) or strs[j][i] != char:
                return prefix
        prefix += char

    return prefix