Introduction

In this blog post, we will explore how to solve the LeetCode problem "179" 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 list of non-negative integers nums, arrange them such that they form the largest number and return it. Since the result may be very large, so you need to return a string instead of an integer. Example 1: Input: nums = [10,2] Output: "210" Example 2: Input: nums = [3,30,34,5,9] Output: "9534330" Constraints: 1 <= nums.length <= 100 0 <= nums[i] <= 109

Explanation

Here's a breakdown of the approach, followed by the Python code:

• Custom Sorting: The core idea is to sort the numbers based on a custom comparison. Instead of numerical order, we compare strings a+b and b+a. The larger combined string indicates the better order. For example, comparing "3" and "30", "330" > "303", so "3" comes before "30".
• String Conversion and Joining: Convert the integers to strings. After sorting, join the strings together.

• Leading Zero Removal: Handle the edge case where the result starts with leading zeros (e.g., "000"). Reduce it to a single "0".

• Time Complexity: O(n log n), dominated by the sorting algorithm. Space Complexity: O(n), to store the string representations of the numbers and potentially auxiliary space used by the sorting algorithm.

Code

    from functools import cmp_to_key

def largestNumber(nums):
    """
    Given a list of non-negative integers nums, arrange them such that they form the largest number and return it.
    Since the result may be very large, so you need to return a string instead of an integer.

    Args:
        nums (list of int): A list of non-negative integers.

    Returns:
        str: The largest number that can be formed by arranging the given numbers.
    """

    def compare(a, b):
        if a + b > b + a:
            return -1  # a should come before b
        elif a + b < b + a:
            return 1  # b should come before a
        else:
            return 0  # a and b are equivalent

    nums_str = [str(x) for x in nums]
    nums_str.sort(key=cmp_to_key(compare))
    result = "".join(nums_str)

    # Handle leading zeros
    result = result.lstrip('0')
    if not result:
        return "0"  # All zeros case
    return result