Contains_Duplicate1.rb

# @param {Integer[]} nums
# @return {Boolean}
def contains_duplicate(nums)
    na = nums.sort
	na.each_index do |i|
		if i<na.length
			return true if na[i]== na[i+1]
		end
	end
	return false
end

Contains_Duplicate2.rb

def contains_duplicate(nums)
    store = {}
    nums.each do |num|
        return true if store[num]
        store[num] = true
    end
    return false
end