Introduction

In this blog post, we will explore how to solve the LeetCode problem "1748" 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 an integer array nums. The unique elements of an array are the elements that appear exactly once in the array. Return the sum of all the unique elements of nums. Example 1: Input: nums = [1,2,3,2] Output: 4 Explanation: The unique elements are [1,3], and the sum is 4. Example 2: Input: nums = [1,1,1,1,1] Output: 0 Explanation: There are no unique elements, and the sum is 0. Example 3: Input: nums = [1,2,3,4,5] Output: 15 Explanation: The unique elements are [1,2,3,4,5], and the sum is 15. Constraints: 1 <= nums.length <= 100 1 <= nums[i] <= 100

Explanation

Here's a solution to the problem of finding the sum of unique elements in an array:

• Frequency Counting: Use a frequency array (or hash map) to count the occurrences of each number in the input array.

• Summation of Uniques: Iterate through the frequency array and add the numbers that appear exactly once to a running sum.

• Runtime Complexity: O(n) where n is the length of the input array. Storage Complexity: O(k) where k is the range of numbers, since we use a frequency array (in this case k is bounded by 100 per the constraints).

Code

    def sumOfUnique(nums: list[int]) -> int:
    """
    Given an integer array nums, return the sum of all the unique elements of nums.
    The unique elements of an array are the elements that appear exactly once in the array.

    Example 1:
    Input: nums = [1,2,3,2]
    Output: 4
    Explanation: The unique elements are [1,3], and the sum is 4.

    Example 2:
    Input: nums = [1,1,1,1,1]
    Output: 0
    Explanation: There are no unique elements, and the sum is 0.

    Example 3:
    Input: nums = [1,2,3,4,5]
    Output: 15
    Explanation: The unique elements are [1,2,3,4,5], and the sum is 15.

    Constraints:
    1 <= nums.length <= 100
    1 <= nums[i] <= 100
    """

    counts = {}
    for num in nums:
        counts[num] = counts.get(num, 0) + 1

    unique_sum = 0
    for num, count in counts.items():
        if count == 1:
            unique_sum += num

    return unique_sum