井，井，井……
Well Well Well...
题目详情
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?
解析
Original Explanation
The diagram presented here shows the depths of the 49 sections after exactly 360 minutes have elapsed. After this moment, the water level will begin to rise on the bottom-right-most section. Thus the answer to this month’s puzzle is 360. Congratulations to everyone who solved this month’s puzzle!