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

Problem Link

Description

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Given an binary array nums 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.

 

Constraints:

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

Solution

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Python3

class Solution:
    def kLengthApart(self, nums: List[int], k: int) -> bool:
        stack = []
        
        for i,x in enumerate(nums):
            if x == 1:
                if stack and i - stack[-1] <= k:
                    return False
                
                stack.append(i)
        
        return True