Problem: Suppose $cnt(i)$ represents the number of occurrences of $i$ in array $A$ of length $n$ whose elements are between $1$ and $n$. An array is called a $k$-good array if and only if $cnt(k)=k$. Let $f(k)$ be the number of all $k$-good arrays. You are to calculate the $\sum\limits_{k=1}^n f(k)$. ↵
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This problem looks like some dp problems which can be reduced to a simper form and solved by Kunth's Mechanical Summation. But I haven't thought up a good solution.↵
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Could you share your ideas about this problem?
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This problem looks like some dp problems which can be reduced to a simper form and solved by Kunth's Mechanical Summation. But I haven't thought up a good solution.↵
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Could you share your ideas about this problem?
