219. Contains Duplicate II-存在重复元素 II

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.

Example 1:
Input: nums = [1,2,3,1], k = 3
Output: true

Example 2:
Input: nums = [1,0,1,1], k = 1
Output: true

Example 3:
Input: nums = [1,2,3,1,2,3], k = 2
Output: false

Solution in python:

class Solution:
    def containsNearbyDuplicate(self, nums: List[int], k: int) -> bool:
        aset = dict()
        for i in range(len(nums)):
            if nums[i] not in aset:
                aset[nums[i]] = i
            elif i - aset[nums[i]] <= k:
                return True
            else:
                aset[nums[i]] = i
        return False