containsDuplicate.md

Contains Duplicate

Problem Statement

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.

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Examples

Example 1:

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

Example 2:

• Input: nums = [1, 2, 3, 4, 5]
• Output: false

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Algorithmic Approach (Using Set or Object)

This problem can be solved optimally using either a Set or an Object to detect duplicate elements. Below is the step-by-step approach:

1. Create an empty Set or Object to store elements from the array.
2. Iterate through the input array using a loop.
3. For each element:
   • If the current element already exists in the Set or Object, return true immediately (indicating duplicates exist).
   • Otherwise, add the current element to the Set or Object.
4. If the loop completes without finding any duplicates, return false.

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Time and Space Complexity

• Time Complexity:
  The time complexity of this algorithm is O(n), where n is the number of elements in the array. This is because we iterate through the array once, and operations like adding or checking membership in a Set or Object are constant time on average.

• Space Complexity:
  The space complexity is O(n) as we use an additional data structure (Set or Object) to store elements from the array.

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