题目描述：查看数组是否有重复且下标距离最大k.
题目链接：Leetcode 219. Contains Duplicate II
代码如下：
class Solution:
def containsNearbyDuplicate(self, nums, k):
dic = {}
for i, v in enumerate(nums):
if v in dic and i - dic[v] <= k:
return True
dic[v] = i
return False