Implement Array.fill

Easy
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Solution Guide: Implement Array.fill

Approach

Iterate over the specified range within the array, replacing each element with the given value. Normalize negative start/end indices by adding the array length, and clamp bounds to prevent out-of-range writes. The operation modifies the array in place and returns it.

Complexity Analysis

Time
O(n)
Space
O(1)

Pattern

Array Polyfill

Why It Works

Negative index normalization and bounds clamping ensure the fill range is valid, while in-place mutation avoids allocating a new array.

Updated Feb 2026