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Solution of a divide-and-conquer maximin recurrence. (English) Zbl 0692.68038

Summary: The solution of the divide-and-conquer recurrence \[ M(n)=\max_{1\leq k<n}(M(k)+M(n-k)+\min (f(k),f(n-k))) \] is found for a variety of functions f. Asymptotic bounds on M(n) are found for arbitrary nondecreasing f, and the exact form of M(n) is determined for f nondecreasing and weakly concave. As a corollary to the asymptotic bounds, it is shown that M(n) remains linear even when f is almost linear. Among the exact forms determined: For \(f(x)=\lfloor lg x\rfloor\), the solution is \(M(n)=(M(1)+1)n-\lfloor lg n\rfloor -\nu (n)\) where \(\nu\) (n) is the number of 1-bits in the binary representation of n. For \(f(x)=\lceil lg x\rceil\), the solution is \(M(n)=(M(1)+1)n-\lceil lg n\rceil -1\), while for \(f(x)=\lceil lg(x+1)\rceil\), the solution is \(M(n)=(M(1)+2)n-\lfloor lg n\rfloor -\nu (n)-1\).

MSC:

68Q25 Analysis of algorithms and problem complexity
68R99 Discrete mathematics in relation to computer science
05A20 Combinatorial inequalities
26A12 Rate of growth of functions, orders of infinity, slowly varying functions
Full Text: DOI

Online Encyclopedia of Integer Sequences:

Total number of 1’s in binary expansions of 0, ..., n.