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Wrap combinatorics memoization caches in let blocks

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commit c8db26ddd7ceffc5d8d648375c62bdf453ff4027 1 parent 1eb7ca4
kmsquire authored
Showing with 44 additions and 39 deletions.
1. +44 −39 base/combinatorics.jl
83 base/combinatorics.jl
 @@ -301,22 +301,24 @@ function nextpartition(n, as) xs end -const _npartitions = (Int=>Int)[] -function npartitions(n::Int) - if n < 0 - 0 - elseif n < 2 - 1 - elseif (np = get(_npartitions, n, 0)) > 0 - np - else - np = 0 - sgn = 1 - for k = 1:n - np += sgn * (npartitions(n-k*(3k-1)>>1) + npartitions(n-k*(3k+1)>>1)) - sgn = -sgn +let _npartitions = (Int=>Int)[] + global npartitions + function npartitions(n::Int) + if n < 0 + 0 + elseif n < 2 + 1 + elseif (np = get(_npartitions, n, 0)) > 0 + np + else + np = 0 + sgn = 1 + for k = 1:n + np += sgn * (npartitions(n-k*(3k-1)>>1) + npartitions(n-k*(3k+1)>>1)) + sgn = -sgn + end + _npartitions[n] = np end - _npartitions[n] = np end end @@ -365,20 +367,21 @@ function nextfixedpartition(n, m, bs) return as end -const _nipartitions = ((Int,Int)=>Int)[] -function npartitions(n::Int,m::Int) - if n < m || m == 0 - 0 - elseif n == m - 1 - elseif (np = get(_nipartitions, (n,m), 0)) > 0 - np - else - _nipartitions[(n,m)] = npartitions(n-1,m-1) + npartitions(n-m,m) +let _nipartitions = ((Int,Int)=>Int)[] + global npartitions + function npartitions(n::Int,m::Int) + if n < m || m == 0 + 0 + elseif n == m + 1 + elseif (np = get(_nipartitions, (n,m), 0)) > 0 + np + else + _nipartitions[(n,m)] = npartitions(n-1,m-1) + npartitions(n-m,m) + end end end - # Algorithm H from TAoCP 7.2.1.5 # Set partitions @@ -429,20 +432,22 @@ function nextsetpartition(s::AbstractVector, a, b, n, m) end -const _nsetpartitions = (Int=>Int)[] -function nsetpartitions(n::Int) - if n < 0 - 0 - elseif n < 2 - 1 - elseif (wn = get(_nsetpartitions, n, 0)) > 0 - wn - else - wn = 0 - for k = 0:n-1 - wn += binomial(n-1,k)*nsetpartitions(n-1-k) +let _nsetpartitions = (Int=>Int)[] + global nsetpartitions + function nsetpartitions(n::Int) + if n < 0 + 0 + elseif n < 2 + 1 + elseif (wn = get(_nsetpartitions, n, 0)) > 0 + wn + else + wn = 0 + for k = 0:n-1 + wn += binomial(n-1,k)*nsetpartitions(n-1-k) + end + _nsetpartitions[n] = wn end - _nsetpartitions[n] = wn end end
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