:orphan:

Contains Duplicate
==================

.. highlight:: none

Problem
-------
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:**

.. container:: example-block

   **Input:** nums = [1,2,3,1]

   **Output:** true

   **Explanation:**

   The element 1 occurs at the indices 0 and 3.

**Example 2:**

.. container:: example-block

   **Input:** nums = [1,2,3,4]

   **Output:** false

   **Explanation:**

   All elements are distinct.

**Example 3:**

.. container:: example-block

   **Input:** nums = [1,1,1,3,3,4,3,2,4,2]

   **Output:** true

**Constraints:**

- ``1 <= nums.length <= 10``\ :sup:```5```
- ``-10``\ :sup:```9```\ ``<= nums[i] <= 10``\ :sup:```9```

.. highlight:: python

Pattern
-------
Array, Hash Table, Sorting

Approaches
----------

.. tab-set::

    .. tab-item:: Hash Set

        **Code**

        .. literalinclude:: ../problems/easy/contains-duplicate/contains_duplicate__hash_set.py
            :language: python
            :lines: 12-

        **Test**

        >>> from contains_duplicate__hash_set import containsDuplicate
        >>> containsDuplicate([1, 2, 3, 1])
        True
        >>> containsDuplicate([1, 2, 3, 4])
        False
        >>> containsDuplicate([1, 1, 1, 3, 3, 4, 3, 2, 4, 2])
        True

        .. autofunction:: contains_duplicate__hash_set.containsDuplicate