Contains duplicate II

Time: O(N); Space: O(N); easy

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

Explanation

nums[0] = nums[3] and 3 - 0 <= 3

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

[2]:

class Solution1(object):
    """
    Time: O(N)
    Space: O(N)
    """
    def containsNearbyDuplicate(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: bool
        """
        lookup = {}
        for i, num in enumerate(nums):
            if num not in lookup:
                lookup[num] = i
            else:
                # If the value occurs before, check the difference.
                if i - lookup[num] <= k:
                    return True
                # Update the index of the value.
                lookup[num] = i
        return False

[3]:

s = Solution1()

nums = [1,2,3,1]
k = 3
assert s.containsNearbyDuplicate(nums, k) == True

nums = [1,0,1,1]
k = 1
assert s.containsNearbyDuplicate(nums, k) == True

nums = [1,2,3,1,2,3]
k = 2
assert s.containsNearbyDuplicate(nums, k) == False