217. Contains Duplicate[E]

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

Description

Given an array of integers, find if the array contains any duplicates.

Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

Example 1:

1
2
Input: [1,2,3,1]
Output: true

Example 2:

1
2
Input: [1,2,3,4]
Output: false

Example 3:

1
2
Input: [1,1,1,3,3,4,3,2,4,2]
Output: true

Solution

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

1
2
3
class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        return len(set(nums)) != len(nums)

219. Contains Duplicate II[E]

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

Description

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:

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

Example 2:

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

Example 3:

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

Solution

1
2
3
4
5
6
7
8
9
10
11
12
13
class Solution:
    def containsNearbyDuplicate(self, nums: List[int], k: int) -> bool:
        by = {}
        for i, v in enumerate(nums):
            if v not in by:
                by[v] = [i]
            else:
                ii = by[v][-1]
                if i - ii <= k:
                    return True
                else:
                    by[v].append(i)
        return False

220. Contains Duplicate III[M]

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

Description

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

Example 1:

1
2
Input: nums = [1,2,3,1], k = 3, t = 0
Output: true

Example 2:

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

Example 3:

1
2
Input: nums = [1,5,9,1,5,9], k = 2, t = 3
Output: false

Solution

1