[leetcode] 219. Contains Duplicate II @ python

原题

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

解法

字典存储数值和对应的index, 如果遇到数值已存在且之前的index与现在的index的距离 <= k, 返回True

代码

class Solution(object):
    def containsNearbyDuplicate(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: bool
        """
        d = collections.defaultdict(list)
        for i, n in enumerate(nums):
            if n in d and i - d[n][-1] <= k:
                return True
            else:
                d[n].append(i)
        return False