I was just pottering around the web and was reading some articles about how many numbers you have to have in a sudoku puzzle in order to be able to solve it uniquely.
It turns out that the lowest number is 17, or at least no-one has actually found any puzzles where 16 givens lead to a solution. I'm not entirely certain if there is a proof that you need at least 17 as it seems to vary depending on which site you go to whether there is a valid proof out there or whether it is simply that no-one has ever found one despite all those computers running trying to make one and therefore almost certain that there isn't one out there!
I was looking in some newspapers and books I have here, and I've never seen a puzzle published in a magazine or newspaper with less than 20 givens as far as I am aware... which makes you think that they must be pretty rare.
What's the least number of givens you've ever seen in a sudoku puzzle?
I'm thinking that it might be because the puzzles in newspapers have symmetrical givens... I wonder what the least number you need in order to solve a sudoku puzzle with symmetrical givens is?!
How to Solve Futoshiki Puzzles In this video we look at the rules of futoshiki and how they work. We examine the greater than and less than signs that are the key addition to standard sudoku rules. Take a look if you're tempted to have a go at this puzzle type...
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