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Formatted question description: https://leetcode.ca/all/1437.html

1437. Check If All 1’s Are at Least Length K Places Away (Medium)

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 <= 10^5
• 0 <= k <= nums.length
• nums[i] is 0 or 1

Related Topics:
Array

Solution 1.

• Java
• C++
• Python
• Go
• TypeScript

• class Solution {
      public boolean kLengthApart(int[] nums, int k) {
          if (k == 0)
              return true;
          int length = nums.length;
          int prevOneIndex = -k - 1;
          for (int i = 0; i < length; i++) {
              if (nums[i] == 1) {
                  if (i - prevOneIndex <= k)
                      return false;
                  prevOneIndex = i;
              }
          }
          return true;
      }
  }
  
  ############
  
  class Solution {
      public boolean kLengthApart(int[] nums, int k) {
          int j = -1;
          for (int i = 0; i < nums.length; ++i) {
              if (nums[i] == 1) {
                  if (j != -1 && i - j - 1 < k) {
                      return false;
                  }
                  j = i;
              }
          }
          return true;
      }
  }
  

• // OJ: https://leetcode.com/problems/check-if-all-1s-are-at-least-length-k-places-away/
  // Time: O(N)
  // Space: O(1)
  class Solution {
  public:
      bool kLengthApart(vector<int>& A, int k) {
          int prev = -k - 1;
          for (int i = 0; i < A.size(); ++i) {
              if (A[i] == 0) continue;
              if (i - prev <= k) return false;  
              prev = i;
          }
          return true;
      }
  };
  

• class Solution:
      def kLengthApart(self, nums: List[int], k: int) -> bool:
          j = -1
          for i, v in enumerate(nums):
              if v == 1:
                  if j > -1 and i - j - 1 < k:
                      return False
                  j = i
          return True
  
  ############
  
  class Solution(object):
      def kLengthApart(self, nums, k):
          """
          :type nums: List[int]
          :type k: int
          :rtype: bool
          """
          left_1 = float("-inf")
          for i, num in enumerate(nums):
              if num == 1:
                  if i - left_1 < k + 1:
                      return False
                  left_1 = i
          return True
  

• func kLengthApart(nums []int, k int) bool {
  	j := -1
  	for i, v := range nums {
  		if v == 1 {
  			if j != -1 && i-j-1 < k {
  				return false
  			}
  			j = i
  		}
  	}
  	return true
  }
  

• function kLengthApart(nums: number[], k: number): boolean {
      let j = -(k + 1);
      for (let i = 0; i < nums.length; ++i) {
          if (nums[i] === 1) {
              if (i - j - 1 < k) {
                  return false;
              }
              j = i;
          }
      }
      return true;
  }
  
  

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