Can anyone hack this solution or prove it correct?

Revision en1, by -Cap1taL-, 2023-12-26 11:58:56

https://codeforces.net/contest/1175/submission/238928196 For judging whether an array of length n is a 1~n permutation, I judged its sum{i^1} sum{i^2} sum{i^3} sum{i^4} and passed. Can anyone hack this solution or prove it correct? please help me :(

Tags hashing, math, divide and conquer, brute force

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en1 English -Cap1taL- 2023-12-26 11:58:56 300 Initial revision (published)