219. Contains Duplicate 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

思路：用字典存数组和下标dic[1]=0，存的时候，如果之前有值，比较新的值下标和之前的差，index-dic[1] <= k,如果小于，返回True，遍历完，返回False

代码：python3

class Solution:
    def containsNearbyDuplicate(self, nums: List[int], k: int) -> bool:
        dic = {}
        for index,value in enumerate(nums):
            if value not in dic:
                dic[value] = index
            else:
                if index-dic[value] <= k:
                    return True
                else:
                    dic[value] = index
        return False