tenka1_2017C
https://gyazo.com/5e556522f06d9b5a2713f8639e0db56c
Thoughts.
Let's go through it.
4hnw=N(nh+hw+wn)
hmm
It's simply made so that if you do a full search, you won't get there in time.
Maybe we should do a full search and sample for small values.
At any rate, mod n shows that Nhw is a multiple of n and so on.
Official Explanation
Searching for three values will not be done in time, but searching for two values will be done in time.
Is f(a,b,c) equal to d for integers a,b,c?" is a narrow decision
Find c from a, b, d and ask, "Is c an integer?" is a broad decision
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