LeetCode 219. Contains Duplicate II

Description

https://leetcode.com/problems/contains-duplicate-ii/

Given an integer array nums and an integer k, return true if there are two distinct indices i and j in the array such that nums[i] == nums[j] and abs(i - j) <= 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

Constraints:

  • 1 <= nums.length <= 105
  • -109 <= nums[i] <= 109
  • 0 <= k <= 105

Explanation

Having a dictionary to track the visited numbers and check if the element value visited and the position meets the requirement.

Python Solution

class Solution:
    def containsNearbyDuplicate(self, nums: List[int], k: int) -> bool:

        visited = {}
        
        for i in range(len(nums)):        
            if nums[i] in visited and abs(i - visited[nums[i]]) <= k:
                return True
            
            visited[nums[i]] = i
            
        return False
  • Time Complexity: O(N).
  • Space Complexity: O(N).

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