Binary Search Explained: Classic Implementation and Two Interview Variants

Short summary

A tutorial explaining binary search from first principles, covering the classic implementation plus two interview variants: finding the first bad version and searching a rotated sorted array. It emphasizes understanding the monotonic-predicate insight that makes binary search applicable beyond simple equality checks. Code examples in Python illustrate common traps like off-by-one errors and loop-termination conditions.

• •Binary search halves the search space each step, yielding O(log N) runtime on sorted or monotonic data
• •Covers three implementations: classic search, first-bad-version predicate search, and rotated-array search
• •Highlights common pitfalls: off-by-one bounds and loop-termination logic differences between exact-match and first-true variants

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