Introduction

In this blog post, we will explore how to solve the LeetCode problem "3289" 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

In the town of Digitville, there was a list of numbers called nums containing integers from 0 to n - 1. Each number was supposed to appear exactly once in the list, however, two mischievous numbers sneaked in an additional time, making the list longer than usual. As the town detective, your task is to find these two sneaky numbers. Return an array of size two containing the two numbers (in any order), so peace can return to Digitville. Example 1: Input: nums = [0,1,1,0] Output: [0,1] Explanation: The numbers 0 and 1 each appear twice in the array. Example 2: Input: nums = [0,3,2,1,3,2] Output: [2,3] Explanation: The numbers 2 and 3 each appear twice in the array. Example 3: Input: nums = [7,1,5,4,3,4,6,0,9,5,8,2] Output: [4,5] Explanation: The numbers 4 and 5 each appear twice in the array. Constraints: 2 <= n <= 100 nums.length == n + 2 0 <= nums[i] < n The input is generated such that nums contains exactly two repeated elements.

Explanation

Here's the approach, complexity analysis, and Python code for identifying the duplicate numbers:

• Hash Map/Set Approach: Use a hash map (or set) to keep track of the numbers encountered. When a number is encountered for the second time, add it to the result list.

• Iterate and Identify: Iterate through the input list nums. For each number, check if it's already in the hash map. If it is, add it to the duplicates list. Otherwise, add the number to the hash map.

• Time & Space Complexity: O(n) time complexity, O(n) space complexity.

Code

    def find_duplicates(nums):
    """
    Finds the two duplicate numbers in an array of integers.

    Args:
    nums (list[int]): A list of integers where each number from 0 to n-1
                       should appear once, but two numbers appear twice.

    Returns:
    list[int]: A list containing the two duplicate numbers.
    """

    seen = set()
    duplicates = []

    for num in nums:
        if num in seen:
            duplicates.append(num)
        else:
            seen.add(num)

    return duplicates