4 ms·
There is always a solution which doesn't require guessing.
by bryans 12y ago
There is always a solution which doesn't require guessing.
- bumbledraven 12y agoI would be very interested to hear an explanation of how to solve the puzzle below without guessing. For reference, the unique solution is on the right. - - - O - - O X X O X O X - - - - X X O O X O X - - - - - O X O X O X O - - - X O X O X O X O X - - - - - X O X O O X X - - X - - O X O X X O O
- 1wd 12y agoOrder to fill in the board (1, 2, 3, ... 9, A, B, C, ... N): B C D O 2 1 X 3 G N 4 X M N H I 5 O F E F X O X L K J 6 A X 9 8 X 7 8 O Reasoning: 1. finish column 2. avoid OOO in row 3. avoid OOO in row 4. avoid OOO in row 5. avoid OOO in column 6. don't duplicate column 6 7. avoid XXX in column 8. wrap XX on both sides 9. finish row A. finish column B. avoid OOO in column C. avoid XXX in column D. finish row E. don't duplicate column 5 F. finish row G. avoid OOO in column H. avoid OOO in column I. avoid XXX in row J. finish column K. avoid OOO in row L. finish row M. finish column N. finish rows
- bumbledraven 12y agoNice work! Step 6 was the one that eluded me. Using that principle I've now been able to solve several boards that I previously thought required guessing.
- 1wd 12y agoYeah, finding step 6 took me much longer than any other step. (Followed by step E.)
- bumbledraven 12y agoDo you see a way to make progress on this one without guessing? O X - - X O X - - O - - - O X X O - - - O - - - O - X O X - X O - - O -