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

Problem

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 <= 10^5

• 0 <= k <= nums.length

• nums[i] is 0 or 1

Solution (Java)

class Solution {
    public boolean kLengthApart(int[] nums, int k) {
        int last = -k - 1;
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] == 1) {
                if (i - last - 1 >= k) {
                    last = i;
                } else {
                    return false;
                }
            }
        }
        return true;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).