Binary search

On a sorted list, each step keeps the half that can still hold the target. Level: standard.

Learning goals

Start in the middle of a sorted list.
Drop the half that cannot hold the target.
Stop when the middle value is the target.

Simulation

Speed

The list is sorted. This is not a search of an unsorted list.

Formulas

Middle. mid = floor((lo + hi) / 2)
Too low. if value < target, lo = mid + 1
Too high. if value > target, hi = mid - 1

Worked example: sorted list 3, 8, 14, 21, 27, 33, 40. Target 27.

Quiz

Answers

Binary search on this page requires the list to be what? Answer: Sorted.
If the middle value is too low, which side is kept? Answer: The right side.

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