index.md

217. Contains Duplicate

Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.

Example 1:

Input: nums = [1,2,3,1] Output: true

Example 2:

Input: nums = [1,2,3,4] Output: false

Example 3:

Input: nums = [1,1,1,3,3,4,3,2,4,2] Output: true

Constraints

1 <= nums.length <= 10^5 -10^9 <= nums[i] <= 10^9

Solution

class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        unique_nums = set()
        for num in nums:
            if num in unique_nums:
                return True
            unique_nums.add(num)
        return False

Thoughts

Initially thought had to do some XOR bit magic to save space. Seems that a straightforward solution got accepted. Time complexity : O(n) Space Complexity : O(n)