Battleship (puzzle)
Encyclopedia
The Battleship puzzle is a logic puzzle based on the Battleship guessing game
Battleship (game)
The game Battleship is a guessing game played by two people. It is known throughout the world as a pencil and paper game which predates World War I. It was published by Milton Bradley Company in 1931 as the pad-and-pencil game "Broadsides, the Game of Naval Strategy".-Description:The game is...

. It and its variants have appeared in several puzzle contests, including the World Puzzle Championship
World Puzzle Championship
The World Puzzle Championship is an annual international puzzle competition run by the World Puzzle Federation. The first one was held in New York in 1992...

, and puzzle magazines, such as Games magazine.

Solitaire Battleship was invented in Argentina by Jaime Poniachik and was first featured in 1982 in the Argentine magazine Humor & Juegos. Battleship gained more widespread popularity after its international debut at the first World Puzzle Championship in New York City in 1992. Battleship appeared in Games magazine the following year and remains a regular feature of the magazine. Variants of Battleship have emerged since the puzzle's inclusion in the first World Puzzle Championship.

Battleship is played in a grid of squares that hides ships of different sizes. Numbers alongside the grid indicate how many squares in a row or column are occupied by part of a ship.

History

The solitaire version of Battleship was invented in Argentina in 1982 under the name Batalla Naval, with the first published puzzles appearing in 1982 in the Spanish magazine Humor & Juegos. Battleship was created by Jaime Poniachik, founder of Humor & Juegos, and Eduardo Abel Gimenez, Jorge Varlotta, and Daniel Samoilovich, who were editors of the magazine.

After 1982, no more Battleship puzzles were published until five years later in 1987, when Battleship puzzles were published in Juegos Para Gente De Mente, a renamed version of Humor & Juegos. The publishing company of Juegos Para Gente de Mente regularly publishes Battleship puzzles in its monthly magazine Enigmas Lógicos.

Battleship made its international debut at the first World Puzzle Championship in New York in 1992 and met with success. The next World Puzzle Championship in 1993 featured a variant of Battleship that omitted some of the row and column numbers. Other variants have emerged since then, including Hexagonal Battleship, 3D Battleship, and Diagonal Battleship.

Battleship was first published in Games magazine in 1993, the year after the first World Puzzle Championship.

Rules

In Battleship, an armada of battleships is hidden in a square grid of 10×10 small squares. The armada includes one battleship
Battleship
A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...

 four squares long, two cruiser
Cruiser
A cruiser is a type of warship. The term has been in use for several hundreds of years, and has had different meanings throughout this period...

s three squares long, three destroyer
Destroyer
In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

s two squares long, and four submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s one square in size. Each ship occupies a number of contiguous squares on the grid, arranged horizontally
Horizontal plane
In geometry, physics, astronomy, geography, and related sciences, a plane is said to be horizontal at a given point if it is perpendicular to the gradient of the gravity field at that point— in other words, if apparent gravity makes a plumb bob hang perpendicular to the plane at that point.In...

 or vertically. The boats are placed so that no boat touches any other boat, not even diagonally.

The goal of the puzzle is to discover where the ships are located. A grid may start with clues in the form of squares that have already been solved, showing a submarine, an end piece of a ship, a middle piece of a ship, or water. Each row and column also has a number beside it, indicating the number of squares occupied by ship parts in that row or column, respectively.

Variants of the standard form of solitaire battleship have included using larger or smaller grids (with comparable changes in the size of the hidden armada), as well as using a hexagonal grid.

Strategy

The basic solving strategy for a Battleship puzzle is to add segments to incomplete ships where appropriate, draw water in squares that are known not to contain a ship segment, and to complete ships in a row or column whose number is the same as the number of unsolved squares in that row or column, respectively. More advanced strategies include looking for places where the largest ship that has not yet been located can fit into the grid, and looking for rows and columns that are almost complete and determining if there is only one way to complete them.

Computers and Battleship

Battleship is an NP-complete
NP-complete
In computational complexity theory, the complexity class NP-complete is a class of decision problems. A decision problem L is NP-complete if it is in the set of NP problems so that any given solution to the decision problem can be verified in polynomial time, and also in the set of NP-hard...

problem. In 1997, former contributing editor to the Battleship column in Games Magazine Moshe Rubin released Fathom It!, a popular Windows implementation of Battleship.

External links

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