Contains Duplicate II
Difficulty: Easy
Category: DSA
Topics: Array, Hash Table, Sliding Window
Asked at: Facebook, Amazon
Given an integer array `nums` and an integer `k`, return `true` _if there are two **distinct indices** _`i`_ and _`j`_ in the array such that _`nums[i] == nums[j]`_ and _`abs(i - j) <= k`.
**Example 1:**
**Input:** nums = [1,2,3,1], k = 3
**Output:** true
```
**Example 2:**
**Input:** nums = [1,0,1,1], k = 1
**Output:** true
```
**Example 3:**
**Input:** nums = [1,2,3,1,2,3], k = 2
**Output:** false
```
**Constraints:**
- `1 <= nums.length <= 105`
- `-109 <= nums[i] <= 109`
- `0 <= k <= 105`