I need the solution for this problem https://cses.fi/problemset/task/3423 thanks you !!
I need the solution for this problem https://cses.fi/problemset/task/3423 thanks you !!
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Ideia: For some number n search for the first i in [1, n] such that n + i is equal to a prime. If no answer exists then it's impossible (because n must be matched with someone). After that you can generate pairs
(n, i), (n-1, i+1), (n-2, i+2), ..., (i, n)
And you reduced the problem from n to i-1. The largest prime gape for numbers ≤ 1e5 is 34 (between 73,577 and 73,607), so basically all cases will reduce at most to the case where n ≤ 33. Then I did some small cases and simply guessforced that there would always be a solution and it passed. Hope this helps!