Henry Ernest Dudeney/Puzzles and Curious Problems/331 - The Siamese Serpent/Solution

Puzzles and Curious Problems by Henry Ernest Dudeney: $331$

The Siamese Serpent

Draw as much of the serpent as possible using one continuous line,

without taking the pencil off the paper or going over the same line twice.

Solution

The drawing cannot be executed under the conditions in fewer than $13$ lines.

The longest of these lines is one which starts at $A$ and ends at $B$ in the diagram.

The dotted lines are the ones which have been omitted.

Thus, the unbroken line from $D$ to $C$ is longer than the broken one, so we take the former.

Again, we get a little more of the drawing by taking the tongue rather than the mouth,

but the part of the tongue ending in a single line has to be omitted.

Sources

• 1932: Henry Ernest Dudeney: Puzzles and Curious Problems ... (previous) ... (next): Solutions: $331$. -- The Siamese Serpent
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Answers: $431$. The Siamese Serpent