Coding Games and Programming Challenges to Code Better
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Created by @VizGhar,validated by @ParzivalX,@cedricdd and @Timinator.
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Hi,
Not yet totaly resolved anyway, to me this puzzle is requesting multiple concepts which make of this a good candidate to place it on hard level.
Did you mind about that ?
Even if the use of Algo X can reduce somehow the complexity, the elaboration of the logic is quite advanced.
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Difficulty levels will always be challenging due to the small number of categories. In my reviewer notes, I said I thought Pips was on the easy end of medium. I don’t think it is significantly more difficult than a lot of the medium exact cover problems already on CodinGame. @VizGhar’s next two, Battleship Solitaire and Magnets, both seem quite a bit more difficult than Pips to me. I see your point on the multiple concepts, but I felt like that was just more work, not necessarily more difficulty.
Considering the relative difficulty in the big picture of all exact cover problems, I’m don’t think medium is misleading. Difficulty is pretty subjective, so I see how medium vs hard could be argued and I wouldn’t be shocked to lose that argument. However, I am going to reaffirm my vote for medium.
Would you consider the same if you prevent yourself to use Algorithm X?
The intrication between the rules and the cumulation of wide zone of rules applications makes this puzzle quite not obvious. I have resolved all medium exept 3 up to now and I can say based on that, the amount of trick is quite high and their diversity also. In the end the choice is subjective, that’s right the harmonization to the means is also key.
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For me AlgorithmX is simply out-of-the-box optimized recursive backtracking algorithm.
It does recursive backtracking + memoization if you use “history” + sorting of moves if you adjust “row selection” + and “steering” it is just necessary custom adjustment. I’ll try to solve this puzzle using plain recursive backtracking and will let you know. I’ve solved the Pips only using AlgoX to be honest.
I was tempted to mark more of my puzzles as hard. Battleship Solitaire and Polyominoes were hottest candidates.
I agree, this one feels more like a Hard than Medium.
It seems to me there is a trend to underestimate the level, compared to a few years ago. I consider this one to be more difficult than some “Very Hard” ones (though these were clearly overestimated), and that probably holds for others in the Medium category.
@Timinator I think that, more often than not, “more work” implies “more difficult”, because every aspect doesn’t fit in your head simultaneously, because there are more opportunities to introduce bugs, which themselves are more difficult to hunt down.
@VizGhar While I agree with your definition of AlgorithmX, we’ll see how you do with plain backtracking, but I suspect you may struggle a bit with timeouts, which would mean the problem becomes more difficult if you don’t have it in your toolbox.
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All good points. @Lanfeust, @jrl86 - how would you compare the difficulty of Pips to There is No Spoon - Episode 2?
Hard to compare a problem I solved 6 years ago in Python without algo_x with one I solved 6 hours ago in Rust with algo_x 
.
At first sight, one doesn’t look obviously harder than the other.
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On my side I have not yet completed this one, but the logic part is way more easy on No spoon (at least more obvious). If you do logic up to the end the most critical is to get the cross link check is the key complexity on my side at least. No optimisation issue there even in python no optimised backtrack is needed (if good logic is used as base).
Pips for me gives less possibilities in term of logic but requires more complicated code for that part for the zonal application of rules. It makes the management more difficult on the backtracking and logic application. This balance the complexity with the management of checking cross links of no spoon 2.
I would juge difficulty similar if I don’t struggle to much on the rest of optimisation on this one…
edit : I finished it, some tricks in the logic alows to get it pass without memoisation optimization. Anyhow the logic is quite on same level than No spoon2. I would maintain my grading as hard.
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