###219. Contains Duplicate II

题目:
<https://leetcode.com/problems/contains-duplicate-ii/>


难度:

Easy 


经过了Contains Duplicate的考验，用hash table（也叫dictionary）来存，这个元素还没出现过，就放hash table，如果出现了，计算相邻距离，小于等于k则return true，否则更新hash table中元素的位置，


我用的sort

```
class Solution(object):
    def containsNearbyDuplicate(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: bool
        """
        if len(nums) < 2 : return False
        lookup = {}
        for i in range(len(nums)):
            if nums[i] not in lookup:
                lookup[nums[i]] = i
            else:
                if i - lookup[nums[i]] <= k :
                    return True
                lookup[nums[i]] = i
        return False
```