In a standard game of battleships, what is the minimum number of strikes you will need to make to guarantee hitting at least one boat?

Battleships is played on a 10x10 Grid,
You are allowed:-
1 Battle Ship (4x1)
2 Cruisers (3x1)
3 Destroyers (2x1) and
3 Submarines (1x1)

NOTE:-These rules are slightly different than those of the board game, I am using these so that all members can give the same answer.

You need 24 shots to ensure you hit the battleship.
The grid will look like this:

X~shot fired there
O~no shot fired

O O O X O O O X O O
O O X O O O X O O O
O X O O O X O O O X
X O O O X O O O X O
O O O X O O O X O O
O O X O O O X O O O
O X O O O X O O O X
X O O O X O O O X O
O O O X O O O X O O
O O X O O O X O O O

This may not look like it does any good, but actually, now you will have to have hit the 4 by 1 ship-the battleship. This is because there is no straight line of 4 squares. Any of the other ships could pass unscathed, but now at lest one of the ships is hit.

Edited on December 22, 2005, 4:29 pm

Posted by saprom on 2005-12-21 22:26:52