LeetCode： Contains Duplicate

Question

Given an array of integers, find if the array contains any duplicates.

Your function should return true if any value appears at least twice in the array, and it should 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: true

Example 3:

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

Output: true

Solution

def contains_duplicate(nums)
  dict= Hash.new(0)
  nums.each do |num|
    dict[num] += 1
    return true if dict[num] > 1
  end
  return false
end