Jane Street Puzzles

Current Puzzle

Well Well Well…

A 7′-by-7′ well is dug. It has a peculiar shape: its depth varies from one 1′-by-1′ section to another, as shown below. Each section is marked with its depth. (E.g., the deepest section is 49′ deep.)

Water is poured into the well from a point above the section marked 1, at a rate of 1 cubic foot per minute. Assume that water entering a region of constant depth immediately disperses to any orthogonally adjacent lower-depth regions evenly along its exposed perimeter.

After how many minutes will the water level on section 43 begin to rise?

Correct Submissions as of 07/06/17

Anthony Clays
Garth Owen
Lok Hin Wong
Calum Heraty
Willem Hoek
Michael Malis
Roderic Day
Abraham Hinteregger
Fosmonaut
Jc
Rogers Epstein
Huehuehue
Hutama
Tamas Kenez
Mufan (Bill) Li

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