# Solving Leetcode Interviews in Seconds with AI: Find the Length of the Longest Common Prefix


	# Introduction
	In this blog post, we will explore how to solve the LeetCode problem "3043" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like [Chatmagic](https://www.chatmagic.app), 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 arrays with positive integers arr1 and arr2. A prefix of a positive integer is an integer formed by one or more of its digits, starting from its leftmost digit. For example, 123 is a prefix of the integer 12345, while 234 is not. A common prefix of two integers a and b is an integer c, such that c is a prefix of both a and b. For example, 5655359 and 56554 have common prefixes 565 and 5655 while 1223 and 43456 do not have a common prefix. You need to find the length of the longest common prefix between all pairs of integers (x, y) such that x belongs to arr1 and y belongs to arr2. Return the length of the longest common prefix among all pairs. If no common prefix exists among them, return 0.   Example 1:  Input: arr1 = [1,10,100], arr2 = [1000] Output: 3 Explanation: There are 3 pairs (arr1[i], arr2[j]): - The longest common prefix of (1, 1000) is 1. - The longest common prefix of (10, 1000) is 10. - The longest common prefix of (100, 1000) is 100. The longest common prefix is 100 with a length of 3.  Example 2:  Input: arr1 = [1,2,3], arr2 = [4,4,4] Output: 0 Explanation: There exists no common prefix for any pair (arr1[i], arr2[j]), hence we return 0. Note that common prefixes between elements of the same array do not count.    Constraints:  1 <= arr1.length, arr2.length <= 5 * 104 1 <= arr1[i], arr2[i] <= 108  

	# Explanation
	Here's a breakdown of the solution:

*   **Convert to Strings:** Transform the integer arrays into arrays of strings. This simplifies prefix comparisons.
*   **Find Minimum Length:** Determine the shortest possible length of a common prefix by finding the minimum length string across all elements in both arrays.
*   **Iterative Comparison:** Iterate from index 0 up to the minimum length. In each iteration, check if the characters at the current index are the same across *all* pairs of strings from `arr1` and `arr2`. If they are not, the longest common prefix is the length found in the previous iteration.

*   **Runtime Complexity:** O(N * M * L) where N is the length of arr1, M is the length of arr2, and L is the length of the shortest string.
*   **Storage Complexity:** O(N + M), to store the string representations of the arrays.

	
	# Code
	```python
	def longest_common_prefix(arr1, arr2):
    """
    Finds the length of the longest common prefix between all pairs of integers (x, y)
    such that x belongs to arr1 and y belongs to arr2.

    Args:
        arr1: A list of positive integers.
        arr2: A list of positive integers.

    Returns:
        The length of the longest common prefix among all pairs.
    """

    str_arr1 = [str(x) for x in arr1]
    str_arr2 = [str(x) for x in arr2]

    min_len = float('inf')
    for s in str_arr1:
        min_len = min(min_len, len(s))
    for s in str_arr2:
        min_len = min(min_len, len(s))

    if min_len == float('inf'):
        return 0

    lcp_len = 0
    for i in range(min_len):
        char = None
        valid = True

        for s1 in str_arr1:
            for s2 in str_arr2:
                if char is None:
                    char = s1[i]
                if i >= len(s1) or i >= len(s2) or s1[i] != s2[i] or s1[i] != char:
                    valid = False
                    break
            if not valid:
                break
        if valid:
            lcp_len += 1
        else:
            break

    return lcp_len
	```