Problem context and objectives
Mission briefing
Signal rescue operator · A beacon is hidden inside an ordered frequency band
Lock onto the signal without testing every frequency: The Rotation Floor.
Each probe costs precious time; searching the wrong half moves the rescue team farther away.
How you win
- 1Recognize when Rotated-array minimum matches the clues
- 2Keep this true after every move: the minimum is inside the inclusive live interval
- 3Reach the result within O(log n)
Rules and pressure
- Target cost: O(log n)
- State rule: the minimum is inside the inclusive live interval
New words in this mission
Open a term for a plain-language explanation.O(log n)+
The work grows by one step when the input roughly doubles. Binary search achieves this by discarding half of the remaining search space each time.
Lesson 1 of 3
The live right value is the reference beacon. If mid is larger, the descending seam is after mid and mid can be safely removed.
Your call · mid=7, right=2. Next boundary move?