Qm
BrainteasersJane StreetCitadel

The treasure map without the gallows

An old map says: "On the island stand an oak, a pine and a gallows. Walk from the gallows to the oak, counting your paces; at the oak turn right by a right angle and walk the same number of paces; drive in a spike. Return to the gallows, walk to the pine counting paces; at the pine turn left by a right angle and walk the same number of paces; drive in a second spike. The treasure lies halfway between the spikes."

You arrive to find the oak and the pine, but the gallows has rotted away without trace.

Can you still find the treasure? Where is it?

Show a hint

Try it with the gallows in two different imagined positions and see whether the treasure moves. Coordinates, or complex numbers, make the algebra one line.

Your answer

Solving needs a free account

Answers, streaks and solutions unlock when you are signed in. Reading the question and the hint stays free.

Discussion

Sign in to join the discussion · reading is open to everyone

💡 Discussion rules

  1. No full solutions here. Hints and approaches only.
  2. Complexity, edge cases and intuition are the point.
  3. Interview experiences are welcome. Respect your NDAs.

Loading discussion…

Learn the concepts

The theory behind this question.

Related questions

The bookworm and the ten volumesDropping needles to estimate piHalving a cake that already has a piece missingTiling a hexagon with lozengesSplitting a deck in the dark
All questions →