Ridiculous Chess Puzzle

Logic Level 5

Take a look at the position below.

White to move.

What is the least amount of moves that white can checkmate black, assuming both sides play optimally?

Also, what is the first move by white?

Give the least amount of moves X the coordinates of the target square $(x,y)$ (the square where the piece will move to, you should add coordinate $x$ + coordinate $y$ ) X the amount of legal moves black can play after white's first move as your answer. The starting rank coordinates is $(0,0)$ .

Try not to use a chess engine when solving this problem!

The answer is 266.

2 solutions

Seth-Riley Adams
Apr 18, 2016

Relevant wiki: Chess Puzzles

This problem was composed by T. Taverner in 1881 1.Rh1!! Whatever black plays, he will be checkmated next move:

If 1...c3 then 2.Nd3# If 1...Bxc7 then 2.Rh4# If 1...Be7 2.e3# If 1...Bf6 2.Qf5# If 1...Bg5 2.Qh2# If 1...Bh4 2.Rxh4# If 1...Bxh7 2.Nd5# If 1...Bf7 2.Qf5# If 1...Be6 2.e3# If 1...Bd5 2.Nxd5# If 1...Rf7 2.Nd5# If 1...Re7 2.Rh4# If 1...Rf6 2.Rh4# If 1...Re6 2.Nd5# If 1...Rf5 2.Qxf5# If 1...Re5 2.Qg4# If 1...Re4 2.fxe4# If 1...Re3 2.Bh2# If 1...Rxe2+ 2.Nxe2#

I got the mate i.e. Rh1 but I didn't understand what you meant for the answer submission. Coordinates of Rh1 is (7,0). Number of moves is 2. So the answer should be $(7+0) \times 2=14$ right?

A Former Brilliant Member - 5 years, 1 month ago

Not completely, but I did mess up with the answer. It's actually supposed to be: $(7+0) \times 2 \times 19$ (amount of legal moves black can play after 1.Rh1) $= 266$ , not 646! :( I will have to repost this problem.

Seth-Riley Adams - 5 years, 1 month ago

I did not see the last part of the problem. Sorry. Not required. A staff member will edit the answer. I have reported the problem and they should probably change the answer soon and give credits to those who marked 266 before.

A Former Brilliant Member - 5 years, 1 month ago

@A Former Brilliant Member – Ok, thanks.

Seth-Riley Adams - 5 years, 1 month ago

@Seth-Riley Adams – Thanks. I've made the relevant edits.

Brilliant Mathematics Staff - 5 years, 1 month ago

I want to know that the question ask that white should make his first move but you gave the solution of black first move

Shivang Gupta - 5 years, 1 month ago

In the first line of the solution, it is given that 1.Rh1

A Former Brilliant Member - 5 years, 1 month ago

The hardest part for me was understanding how to formulate the answer. Including counting black's possible moves!

Cool puzzle.

Steven Perkins - 5 years ago

Awesome puzzle. I was looking for a mate in 3 as there are many mate in 4 possibilities. I certainly missed the 'White Queen to H2' after 'Black Bishop G5' which may have helped in considering the possibility of a mate in 2 as Rook H1 was something I was considering among other moves. So yeah 19 legal moves for black, mate in 2 and coordinates are (7,0): 7 x 19 x 2.

Zaid Ahmed - 1 year, 9 months ago

Patrick Corn
May 24, 2016

The key is 1 Rh1; White mates in two. This is a famous problem; the arrangement of black's rooks and bishops was dubbed "organ pipes" by Sam Loyd. See this article for more examples.

Ridiculous Chess Puzzle

The answer is 266.

2 solutions

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