31
$\begingroup$

The absent-minded king has gotten himself lost. Help him return to his palace on h8 using as few moves as possible.

Only legal chess moves are allowed. Pawns are not promoted on the final rank.

You can post your solutions in quasi-algebraic notation. For example, moving the rook from e7 to e8 can be notated as Re7e8. Or you can post them as animations.

enter image description here

(Click on the image for a virtual board.)

The current best solution is by Arthelais at 70 moves.

Credit for the name of this puzzle goes to Dr Xorile.

Improve this question
$\endgroup$
7
  • 4
    $\begingroup$ This... looks... fun... $\endgroup$
    – greenturtle3141
    Commented Nov 28, 2016 at 5:34
  • $\begingroup$ Can the pawns move diagonally as they do when capturing a piece? $\endgroup$
    – Sid
    Commented Nov 28, 2016 at 7:25
  • 2
    $\begingroup$ @Sid, the pawns cannot move diagonally because there is nothing to capture. $\endgroup$
    – DyingIsFun
    Commented Nov 28, 2016 at 7:57
  • 1
    $\begingroup$ +1 for the combo [chess] [sliding-blocks] and because it looks more impressive than the Ugren problem I posed & tagged with this combo. $\endgroup$
    – Rosie F
    Commented Nov 28, 2016 at 8:20
  • 2
    $\begingroup$ @RosieF, yours is also a great puzzle that I missed. For any others, who may also have missed it, her's the link: help black slide the blocks to solve this chess problem $\endgroup$
    – Dr Xorile
    Commented Nov 28, 2016 at 19:34

3 Answers 3

Reset to default
23
$\begingroup$

Here's a solution (at least the upper bound of 125 moves). I've outlined it, to emphasize the key logic, and created an animation to show the whole solution):

Get the knight from c8 to d1 (moving the rooks on d&e); Also get the Bishop from f8 to e1; get the bishop from b8 to b2 moving the pawns up); Na2c3 (recently vacated by the bishop); Ka1a2; Bb2a1; Ka2b2; Nc3a2; Kb2c3; Nd1b2. At this point your king is ready to plunge into the Rook River.
Get the king out to d3; push the pawn c2c3; Rd2c2; clear the rooks to move the Nb2d1, filling in the gap with the rooks. Send the Knight up the river d1e3d5e7; clear the Rook at f8; Nh7f8; Bg8h7;Ne7g8; Bring the King up the river and replace the Knight on f8; Ng8e7; Kf8g8; f7f8; Nh8f7; Kg8h8
Solution Animation

Improve this answer
$\endgroup$
8
  • 3
    $\begingroup$ "Rook River" is a fantastic name for this puzzle! I would rename it if you'd be so kind as to lend me the phrase? (Of course I would attribute it to you in the body of the puzzle.) But if you don't want to, that's fine too! $\endgroup$
    – DyingIsFun
    Commented Nov 28, 2016 at 13:13
  • $\begingroup$ Of course you can! $\endgroup$
    – Dr Xorile
    Commented Nov 28, 2016 at 14:57
  • $\begingroup$ How do you replace the bishops on f8 and g8 with knights? $\endgroup$
    – Sid
    Commented Nov 28, 2016 at 14:59
  • $\begingroup$ There is a bishop at f8. Rd2d3- Did you mean Rd2-c2? $\endgroup$
    – Sid
    Commented Nov 28, 2016 at 15:27
  • $\begingroup$ See italicized text. I got the Bishop down to e1, replacing it with a rook $\endgroup$
    – Dr Xorile
    Commented Nov 28, 2016 at 15:32
14
$\begingroup$

Using Dr Xorile's answer as a base here is an improved solution:

It uses a total of $91$ moves.
animated gif of given solution
Each move is listed below as the square from which to move a piece

  1. e7;  2. c8;  3. d8;  4. d7;  5. d6;  6. d5;  7. e7;  8. f8;  9. e8; 10. d8;
 11. c8; 12. c7; 13. b8; 14. b7; 15. b6; 16. c7; 17. c6; 18. c5; 19. b6; 20. b5;
 21. b4; 22. c5; 23. c4; 24. c3; 25. b4; 26. b3; 27. b2; 28. c3; 29. a2; 30. a1;
 31. b2; 32. a2; 33. c3; 34. d5; 35. d4; 36. d3; 37. d2; 38. d1; 39. c3; 40. b2;
 41. d1; 42. d2; 43. d3; 44. d4; 45. c3; 46. c2; 47. d2; 48. d1; 49. b2; 50. c2;
 51. d2; 52. e2; 53. e3; 54. d1; 55. d2; 56. d3; 57. d4; 58. d5; 59. e3; 60. e4;
 61. d3; 62. d4; 63. e4; 64. e5; 65. e6; 66. d6; 67. e7; 68. d5; 69. e5; 70. d4;
 71. d5; 72. e5; 73. e6; 74. d5; 75. e5; 76. d6; 77. d7; 78. d8; 79. e8; 80. f8;
 81. h7; 82. g8; 83. e7; 84. e6; 85. f8; 86. e7; 87. g8; 88. f8; 89. f7; 90. h8;
 91. g8

Improve this answer
$\endgroup$
3
  • 3
    $\begingroup$ Note: I think Dr Xorile should get the green tick, I would not have got this without their answer! $\endgroup$
    – Jonathan Allan
    Commented Nov 29, 2016 at 7:00
  • $\begingroup$ Well done! My best was only 108 moves. $\endgroup$
    – DyingIsFun
    Commented Nov 29, 2016 at 7:24
  • 1
    $\begingroup$ Very nice optimization. $\endgroup$
    – Dr Xorile
    Commented Nov 29, 2016 at 14:01
7
$\begingroup$

I found the following 70 move solution:

e7 f8 e8 d8 e7 c8 c7 b8 b7 b6 c7 d8 e8 f8 h7 g8 e7 d7 f8 e8 d8 c7 c6 c5 d7 d6 d5 d4 d3 c5 b6 b5 b4 c5 c4 c3 b4 b3 b2 c3 a2 a1 b2 a2 c3 b2 d3 d4 c3 d3 e3 e4 e5 d4 d5 d6 e5 e6 d6 d7 e7 e8 f8 f7 e6 e7 g8 f7 h8 g8

My solution is inspired by Jonathan Allan's.

Could someone explain to me how I can make an animation like the other responders did?

Improve this answer
$\endgroup$
3
  • $\begingroup$ Very well done! I'd be interested in knowing how users are creating animations too. Maybe they are taking screenshots and using a GIF generator? $\endgroup$
    – DyingIsFun
    Commented Nov 29, 2016 at 19:00
  • $\begingroup$ This notation is illegible to me. How is e7 even a first possibile move? And the pieces aren't even stated anywhere in it! $\endgroup$
    – Rewan Demontay
    Commented Aug 21, 2019 at 17:37
  • 1
    $\begingroup$ There is only one free square at any given move. Each move in the sequence indicates the piece that is moving to the free square. $\endgroup$
    – Arthelais
    Commented Aug 22, 2019 at 18:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.