LeetCode 1437. Check If All 1’s Are at Least Length K Places Away

Description

https://leetcode.com/problems/check-if-all-1s-are-at-least-length-k-places-away/

Given an array nums of 0s and 1s and an integer k, return True if all 1’s are at least k places away from each other, otherwise return False.

Example 1:

Input: nums = [1,0,0,0,1,0,0,1], k = 2
Output: true
Explanation: Each of the 1s are at least 2 places away from each other.

Example 2:

Input: nums = [1,0,0,1,0,1], k = 2
Output: false
Explanation: The second 1 and third 1 are only one apart from each other.

Example 3:

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

Example 4:

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

Constraints:

  • 1 <= nums.length <= 105
  • 0 <= k <= nums.length
  • nums[i] is 0 or 1

Explanation

Find the distance between 1’s and check if all distance are at least k places away..

Python Solution

class Solution:
    def kLengthApart(self, nums: List[int], k: int) -> bool:
        
        i = None
        for j, num in enumerate(nums):     
            if num == 1:                  
                if i != None and j - i <= k:
                    return False
                
                i = j
            
        return True
  • Time Complexity: O(N).
  • Space Complexity: O(1).

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