Merge pull request #55 from davidavdav/nthperm-speed

nthperm(): Replace one `%=` by a `-= remainder * divisor` computed earlier

Author: mschauer

src/permutations.jl

@@ -152,11 +152,10 @@ function nthperm!(a::AbstractVector, k::Integer)
     0 < k <= f || throw(ArgumentError("permutation k must satisfy 0 < k ≤ $f, got $k"))
     k -= 1 # make k 1-indexed
     for i=1:n-1
-        f = div(f, n - i + 1)
-        j = div(k, f) + 1
-        k = k % f
-
-        j = j+i-1
+        f ÷= n - i + 1
+        j = k ÷ f
+        k -= j * f
+        j += i
         elt = a[j]
         for d = j:-1:i+1
             a[d] = a[d-1]