Data commit

Task/Vampire-number/Julia/vampire-number-1.julia

@@ -0,0 +1,34 @@
+function divisors{T<:Integer}(n::T)
+    !isprime(n) || return [one(T), n]
+    d = [one(T)]
+    for (k, v) in factor(n)
+        e = T[k^i for i in 1:v]
+        append!(d, vec([i*j for i in d, j in e]))
+    end
+    sort(d)
+end
+
+function vampirefangs{T<:Integer}(n::T)
+    fangs = T[]
+    isvampire = false
+    vdcnt = ndigits(n)
+    fdcnt = vdcnt>>1
+    iseven(vdcnt) || return (isvampire, fangs)
+    !isprime(n) || return (isvampire, fangs)
+    vdigs = sort(digits(n))
+    d = divisors(n)
+    len = length(d)
+    len = iseven(len) ? len>>1 : len>>1 + 1
+    for f in d[1:len]
+        ndigits(f) == fdcnt || continue
+        g = div(n, f)
+        f%10!=0 || g%10!=0 || continue
+        sort([digits(f), digits(g)]) == vdigs || continue
+        isvampire = true
+        append!(fangs, [f, g])
+    end
+    if isvampire
+        fangs = reshape(fangs, (2,length(fangs)>>1))'
+    end
+    return (isvampire, fangs)
+end

Task/Vampire-number/Julia/vampire-number-2.julia

@@ -0,0 +1,38 @@
+using Printf
+
+function showvampire{T<:Integer}(i::T, n::T, fangs::Array{T,2})
+    s = @sprintf "%6d  %14d %s\n" i n join(fangs[1,:], "\u00d7")
+    for i in 2:size(fangs)[1]
+        s *= " "^23*join(fangs[i,:], "\u00d7")*"\n"
+    end
+    return s
+end
+
+vgoal = 25
+vcnt = 0
+dcnt = 0
+println("Finding the first ", vgoal, " vampire numbers.")
+println("     N         Vampire Fangs")
+while vcnt < vgoal
+    dcnt += 2
+    for i in (10^(dcnt-1)):(10^dcnt-1)
+        (isvampire, fangs) = vampirefangs(i)
+        isvampire || continue
+        vcnt += 1
+        print(showvampire(vcnt, i, fangs))
+        vcnt < vgoal || break
+    end
+end
+
+test = [16758243290880, 24959017348650, 14593825548650]
+println()
+println("Checking a few numbers.")
+println("     N         Vampire Fangs")
+for (i, v) in enumerate(test)
+    (isvampire, fangs) = vampirefangs(v)
+    if isvampire
+        print(showvampire(i, v, fangs))
+    else
+        println(@sprintf "%6d  %14d is not a vampire" i v)
+    end
+end