Forward-Fill Nulls
MediumData EngineeringArray
Description
Given an array nums where some entries are null, replace each null with the most recent non-null value before it. A leading null (no prior value) stays null. Return the filled array.
Examples
Input:
nums = [1,null,null,2,null]Output:
[1,1,1,2,2]Explanation:
Carrying the last seen value forward over nulls yields [1,1,1,2,2].
Input:
nums = [null,3,null]Output:
[null,3,3]Explanation:
Carrying the last seen value forward over nulls yields [null,3,3].
Input:
nums = [5,6,7]Output:
[5,6,7]Explanation:
Carrying the last seen value forward over nulls yields [5,6,7].
Constraints
- •
1 ≤ nums.length ≤ 10⁴