Contains Duplicate
Updated Jan 31, 2026
Problem
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.
Constraints
1 <= nums.length <= 10^5
-10^9 <= nums[i] <= 10^9
Examples
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
Function Signature
def containsDuplicate(self, nums: list[int]) -> bool
How to Submit
Implement a Solution class with a containsDuplicate method.
Your method will be called with the input parameters and should return the answer.