LeetCode： Contains Duplicate II

Question

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most 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

Solution

def contains_nearby_duplicate(nums, k)
  dict = {}
  nums.each_with_index do |num, index|
    return true if dict[num] && (index - dict[num] <= k)
    dict[num] = index
  end
  return false
end