Sudoku and Battleships are both grid-based logic puzzles you solve by pure deduction, so solvers naturally wonder how alike they really are. The short answer: Battleships is moderate to Sudoku. Below we lay out what the two share, where they part ways, and whether the skills you have built on Sudoku will carry over.
- Grid: Rectangular (usually 10×10)
- Closeness to Sudoku: Moderate
- Also called: Bimaru, Solitaire Battleships, Yubotu
What is Battleships?
Place a known fleet of ships in the grid so each row and column holds the stated number of ship segments, no two ships touch — not even diagonally — and the given hints are respected. Here are the rules in full:
- A fixed fleet (e.g. one 4-cell battleship, two 3-cell cruisers, three destroyers, four submarines) must be placed; every cell is either ship or water.
- The number beside each row and column says how many of its cells are ship segments.
- Ships are straight, do not overlap, and never touch another ship — not even diagonally; a handful of given cells (a ship piece or water) start you off.
What Battleships looks like
The grey numbers count the ship segments in each row and column. You place the fleet so those totals match, no two ships touch (not even at a corner), and any given cells are respected. Here is a small solved board with a two-cell ship and a one-cell submarine.
Navy = ship segments, pale blue = water. Column 1 needs 2 (the vertical two-cell ship), column 4 needs 1 (the lone submarine); the water ring around each ship is forced by the no-touching rule.
Read a line's total, subtract the ships already placed, and the rest of the line is forced — exactly the counting you do when a Sudoku unit is nearly full. The extra "ships can't touch" rule is a bonus: every ship you place immediately floods its neighbours with water, cascading fresh certainties.
What Battleships shares with Sudoku
- Both are constraint-satisfaction puzzles: the row and column totals pin down each line exactly as a Sudoku clue constrains its unit.
- The decisive move is shared — when a line's count is already met, every remaining cell is forced to water, just as a completed Sudoku unit forces the rest.
- A proper puzzle has one solution reachable by deduction; the no-touching rule cascades certainties the way Sudoku eliminations do.
How Battleships differs from Sudoku
- You place multi-cell ships of set shapes, not single digits, so the fleet inventory is part of the constraint.
- The no adjacency rule (ships can't touch, even at corners) has no Sudoku equivalent — it is the puzzle's signature.
- Cells are essentially binary (ship or water) rather than one of nine digits.
Do Sudoku skills transfer?
The row-and-column counting you do in Sudoku carries straight over: read a line's total, subtract what is already placed, and every leftover cell is forced. Battleships just adds the "ships can't touch" rule, which spreads water around each segment automatically.
Brush up on the technique that carries over: Crosshatching.
The verdict
Battleships is Sudoku's per-line counting and no-guess deduction applied to a fleet — same bookkeeping, plus a no-touching rule that does half the work for you.