Enigmas & puzzles

July 22, 2005
Big Uglyville subway

"We're gonna build a subway," the mayor said. "We got nine shopping malls in Uglyville, and we're gonna link 'em all together so that people can get from one to another without using their cars an' pollutin' our beautiful city."

He pointed to a map on the wall, which showed the nine malls. They formed a perfect 3x3 square array, like this:

"Great idea, boss," said the city engineer. "I'll get the boys working on some plans."

"Yeah. I want one single line that runs from Fat Food Franchise to Deep Pan Plaza, with a station at every mall."

"How about this?" asked the city engineer, sketching rapidly on a legal pad.

"Nah. For starters, it don't end at Deep Pan Plaza. And it's got four bends. Rekkit construction tells me that straight tunnels is easy, but bends, they cost. The budget allows for no more than three bends."

The city engineer scratched his head. "Can the line cross itself?"

"Sure. We can put in a stop-light. But not at a station, that'd confuse folks."

What plan would work for the city engineer?


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The answer

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The winner was David Paterson from Croydon