Contains Duplicate

Links

Go to my solution
Go to the question on LeetCode

My Thoughts

What Went Well
I remembered sets and their properties.

What I Learned
I learned how to solve this problem using javascript to remove some rust. I also learned how to create a visual for this problem since I couldn’t find one online.

Comments
Due to how much syntactic sugar python has, this was the fastest I’ve ever, and will ever, complete a question.

Another approach to this problem could be the use of a hash table or dictionary. You can iterate through the nums array and add elements into the dictionary until you encounter an element already inside the dictionary. This approach is viable because of dictionaries’ O(1) access time.

Data Structure Description

Hash Table (Set) - An unordered container of non-repeating values.
Hash Map (Dictionary) - A data structure that maps keys to their values. Each key may only appear once.

Visual Examples
An array being transformed into a set, click to view

Illustration of key value pair mapping, click to view

Solution Statistics

Time Spent Coding
50 Seconds

Time Complexity
O(n) - All the array elements must be duplicated and counted. All the elements in the set must also be counted. These operations are O(n), resulting in the O(n) time complexity.

Space Complexity
O(n) - If the array does not contain duplicates, the set will have n elements, resulting in the O(n) space complexity.

Runtime Beats
88.26% of other submissions

Memory Beats
79.5% of other sumbissions

Solution

class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        # ***Explanation of the oneliner***
        #
        # s = set(nums)
        #
        # Since a set can not contain duplicates if the lengths are not equal
        # then the nums array must contain duplicates
        # if len(nums) != len(s):
        #   return False
        #
        # else:
        #   return True

        return len(nums) != len(set(nums))