Puzzles that have people stumped
Puzzles from contributors looking for help and adviceList of contributions in 'How to solve ?'
| How to solve ? |
| Seeking advice on how best to solve a puzzle. Contributors have uploaded puzzles for you to look at and help them to solve
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| Stuck on puzzle (re: How to solve ?) contributed by Lynne |
| I am stuck. Please help. I have solved all the easy squares and can not find one that I can see that is easy to solve. What is the best strategy to apply (puzzle attached for you to download and look at).  Download this puzzle Click here to download this puzzle
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| Solution ahoy! (re: Stuck on puzzle) contributed by Alexander |
| Although there are no obvious allocations as far as SudokuDragon is concerned there are two squares that are fairly easy to solve and should provide the key to solving the complete puzzle. The squares I have spotted are Bb and Ac. Row A is crucial, there are only a '4' and '5' missing in this row so '4' and '5' must be in Ab and Ac and therefore they can not be in any other square within the region - especially Bb. For Bb the only other possibility is a '9' so a '9' must be allocated in Bb. Also the square Ac must be either a '4' or '5' and nothing else. However there must be a '4' in column b but the only squares a '4' can go are Ab; Bb or Cb. Because it must be in one of these '5' can't got in Ac so Ac is forced to be a '5'. Hope this helps.
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| Stuck again (re: How to solve ?) contributed by CheckAcc |
This puzzle has me stumped. What should I do next to try and solve it ? Download this puzzle Click here to download this puzzle
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| A possible strategy (re: Stuck again) contributed by Alexander |
| As far as I can see there are no obvious to squares to solve first. I tend to look for nearly complete groups - (rows, columns or regions). In this case row A and column g are both missing two squares. The two symbols missing in both cases happen to be '4' and '9'. If you use the SudokuDragon possibility bar and click on '4' you will see that it is going to be critical as to where the '4' is allocated. Use the same techique for '9'. There is a chain of reasoning here. If '9' rather than '4' goes in Ad then that forces a '9' in Fe as it is the only square in column e it can go. If now look for allocating in row E a '9' must go in Eh as it is the only square that can take a '9' now. The region Ag is now crucial as to where the '9' can go - only two squares are possible Cg and Ci. But it can't go in Cg because row i has only one place for a '9' Ci. So it looks like Ci is the place - but this is where the clinch is made. The symbols '1';'3' and '6' must occur in the region Ag in the squares Bi Ch and Ci. This forms a triplet and it means '9' can not go in Ci. So this route has failed the '9' must and can not go in Ci so the initial assumption of '9' in Ad must be wrong. The '4' must be the correct choice for Ad. After that it must be plain sailing. Download the puzzle and see if you can spot any easier strategy than that.
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| Submit2283 (re: How to solve ?) contributed by Huw |
Beginner Download this puzzle Click here to download this puzzle
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| Getting started (re: How to solve ?) contributed by Alexander |
| Well Geraldine, the most important sudoku strategy to learn to start with is the two out of three rule. What you do is look through all the rows and then all columns looking for each number in turn and look for rows in which you get 2 rows or columns out of three that have already been solved. In this case scan the 1s by rows - this does not help as there is only one 1 in square Fb. Now look at the 2s, no luck in rows A;B;C but there is in row E (Ei) and F (Fe) these two 2s in a group of three rows mean a 2 must occur in row D and it's also certain that it must be in column a;b; or c. Only Da is free so the 2 must go in Da. Next look at the rows G;H;I there is a 2 in Gg and Ic so once again it can be proven that the missing 2 in row H must be in column d;e; or f. Now it can't go in He because of the 2 in Fe so the only square left in this row it can go in is square Hf. That's 2 squares solved. Continue looking through the rows, this time for 3s. In rows A;B;C there are two 3s in Ba and Ch so the 3 must be in Ad or Ae. At this time it can't be determined which of the two it is, this often happens. There are no more 3s in the remaining rows so can move on to 4s. With 4s in rows A;B;C there are two once again in Ai and Cc restricting the choice to Bd or Be - can't quickly determine which. Now with rows D;E;F you sport two in Dh and Ea so that leaves a 4 to go in Fd or Ff. Because of the 4 in Gf it cant go in Ff so it must go in Fd. I think that's enough to show the general two out of three strategy in action. You continue with rows going throughh 5;6;7;8 and finally 9. When that is done you do the columns in just the same way working through the numbers 1 to 9. If you solve any squares that means you might find more to solve the next time around - you get to be able to do the scan very quickly and what is wonderful is that you do not need to write anything down - you can do it in your head - and that really impresses people.
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| Submit752 (re: How to solve ?) contributed by bkprice |
I am stumped and there are no hints available. Can you tell me what I should do next ? Download this puzzle Click here to download this puzzle
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| Less stuck? (re: Submit752) contributed by Alexander |
| Looking at the puzzle and SudokuDragon does not currently help with this, there are some possibilities that can be discounted. Most are related to 'chains'. If you look at the Strategy page on this site you'll find something about them under 'General permutation rule' basically if you have a group of {1,4} {4,7} and {4,7,8} and these are the only occurrences of 1,4 and 7 in the group you can discount the '8' as a possibility. Here goes then. In column c there is a chain 23,34,45,56,62 this means 4 in Cc can be discounted. In row A there is a chain 46,67,74 so 4 as a possibility in Ah can be knocked out. In row H there is a chain 15,56,61 so 6 as a possibility in Hh can be knocked out. Is this helping at all? I think there are a few more to find using the same strategy. In
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