217. Contains Duplicate; 219. Contains Duplicate II; 220. Contains Duplicate III ?

217. Contains Duplicate
class Solution(object):
    def containsDuplicate(self, nums):
        """
        :type nums: List[int]
        :rtype: bool
        """
        freq = {}
        result = False
        for num in nums:
            if num not in freq:
                freq[num] = 1
            else:
                result = True
                break
        return result



219. Contains Duplicate II

class Solution(object):
    def containsNearbyDuplicate(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: bool
        """
        num_ind={}
        n=len(nums)
        for i in range(len(nums)):
            if nums[i] in num_ind and abs(i - num_ind[nums[i]]) <= k:
                return True
            num_ind[nums[i]] = i
        return False