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How it works
Binary search works on a sorted array. Compare the middle value with the target, then keep only the half that can contain it. Repeat until you find a match or the candidate range is empty.
Watch the low, mid, and high pointers. The dimmed cells have been ruled out. Each comparison cuts the search space roughly in half: O(log n) time and O(1) extra algorithm space. The visualization stores steps for replay; that is separate from the algorithm’s space complexity.
Duplicates are allowed. This version returns any matching index, not necessarily the first. An empty array has no match.