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Puzzle #138: Traffic Flow in Floyd’s Knob | Alok Goyal's Puzzles Page

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Puzzle #138: Traffic Flow in Floyd’s Knob

Posted on April 16, 2016 by Alok Goyal

This is a very nice “maze” puzzle, borrowed from Martin Gardner’s book “The Colossal Book of Short Puzzles and

Problems” Problem 10.14. The puzzle first appeared in 1962, in Martin Gardner’s Scientific American column. It was created

decision. When the town awoke one morning, it found that a profusion of signs had been erected establishing numerous one

way streets and confusing restrictions on turns.

The citizens were all for tearing down these signs until the police chief, another cousin of the mayor, made a surprising

discovery. Motorists passing through town became so exasperated that sooner or later they made a prohibited turn. The police

chief found that the town was making even more money from these traffic violations than from its speed trap on an outlying

country road.

Of course everyone was overjoyed, particularly because the next day was Saturday and Moses McAdam, the county’s richest

farmer, was due to pass through the town on his way to the county seat. They expected to extract a large fine from Moses,

believing it to be impossible to drive through town without at least one traffic violation. But Moses had been secretly

studying the signs. When Saturday morning came, he astonished the entire town by driving from his farm through town to the