217-contains_duplicate.py

"""

https://leetcode.com/problems/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

"""

from collections import defaultdict

def containsDuplicate(nums: list[int]) -> bool:
    counts = defaultdict(int)
    for num in nums:
        if counts[num] == 1:
            return True
        counts[num] += 1
    return False

if __name__ == '__main__':
    nums = [1,2,3,1]
    print(containsDuplicate(nums))