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Difficult Killer Sudoku Friday July 5th 2019 https://www.calcudoku.org/forum/viewtopic.php?f=16&t=1156 
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Author:  paulv66 [ Sat Jul 06, 2019 9:55 am ] 
Post subject:  Difficult Killer Sudoku Friday July 5th 2019 
I thought the March 22nd puzzle was difficult, but yesterday's puzzle brings it to a whole new level! I don't know how long I've spent on this so far, but I think it must add up to several hours. I made several attempts at it yesterday and thought I had narrowed down the number of possibilities by a process of elimination. I went back to it this morning and thought I had finally cracked it until I got stuck again with a few cells to go. 
Author:  paulv66 [ Sat Jul 06, 2019 11:07 am ] 
Post subject:  Re: Difficult Killer Sudoku Friday July 5th 2019 
Cracked it! I had been concentrating on solving one side of the puzzle, so I decided to switch over to the other side. Once I did this, the solution fell into place after a few false starts. Be interesting to see how many people in total solve it. To date there are only 77. The total number of solvers for the previous four Fridays were 229, 233, 268 and 338 respectively. 
Author:  paulv66 [ Mon Jul 08, 2019 11:24 am ] 
Post subject:  Re: Difficult Killer Sudoku Friday July 5th 2019 
paulv66 wrote: Be interesting to see how many people in total solve it. To date there are only 77. The total number of solvers for the previous four Fridays were 229, 233, 268 and 338 respectively. The final tally is 98, which is significantly less than the previous 4 weeks. I presume this number doesn't include anyone who solved it outside the time limit (I.e. after the solution became available), although I guess someone who was determined enough might have kept going after the time limit was up. Either way, it shows that I certainly wasn't the only one who struggled with this particular puzzle. 
Author:  pnm [ Mon Jul 08, 2019 2:02 pm ] 
Post subject:  Re: Difficult Killer Sudoku Friday July 5th 2019 
I ran some stats on the Friday Killer Sudoku, starting from the date when you first had 2 days to solve it (Feb. 17th, 2017). The percentage below is compared to the number of 4x4 easy puzzles solved (to "normalize" the number somewhat). Code: rank. [date] [percentage] [nr times] 1. [20171027] [7.6] [71] 2. [20190705] [10.7] [88] 3. [20181102] [11.66] [101] 4. [20170602] [12.01] [97] 5. [20170303] [12.12] [100] 6. [20171215] [13.36] [125] 7. [20171201] [13.49] [124] 8. [20171013] [13.73] [125] 9. [20170630] [13.91] [117] 10. [20180302] [14.34] [133] So it's up there alright 
Author:  paulv66 [ Mon Jul 08, 2019 9:51 pm ] 
Post subject:  Re: Difficult Killer Sudoku Friday July 5th 2019 
Thanks Patrick. A bit of an outlier, alright! 
Author:  michaele [ Tue Jul 09, 2019 1:34 pm ] 
Post subject:  Re: Difficult Killer Sudoku Friday July 5th 2019 
This puzzle is a good example of the benefit of adding cages in situations that don't seem helpful at first look. If you add all cages in the top 2 rows excluding cage g2 and cage h2, the total is 85, therefore g2+h2=b3+5. This doesn't seem very helpful, but it is the key to solving this puzzle. 
Author:  pnm [ Mon Jul 15, 2019 3:39 pm ] 
Post subject:  Re: Difficult Killer Sudoku Friday July 5th 2019 
For reference, this is the puzzle in question: 
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