Data update

Task/Digital-root-Multiplicative-digital-root/Pluto/digital-root-multiplicative-digital-root.pluto

@@ -0,0 +1,64 @@
+local bigint = require "pluto:bigint"
+local fmt = require "fmt"
+
+local zero = bigint.new(0)
+local one  = bigint.new(1)
+
+-- Only valid for n > 0 && base >= 2.
+local function mult(n, base)
+    local m = one
+    while m > zero and n > zero do
+        local q, rem = n:div(base)
+        m *= rem
+        n = q
+    end
+    return m
+end
+
+-- Only valid for n >= 0 and base >= 2.
+local function mult_digital_root(n, base)
+    base = bigint.new(base)
+    local m = n
+    local mp = zero
+    while m >= base do
+        m = mult(m, base)
+        mp += one
+    end
+    return {mp, tonumber(m:hex(), 16)}
+end
+
+local base = 10
+local size = 5
+
+local tests = {
+    123321, 7739, 893, 899998,"18446743999999999999", 3778888999, "277777788888899"
+}
+
+local test_fmt = "%20s %3s %3s"
+fmt.print(test_fmt, "Number", "MDR", "MP")
+for tests as test do
+    local n = bigint.new(test)
+    local mpdr = mult_digital_root(n, base)
+    fmt.print(test_fmt, n, mpdr[2], mpdr[1])
+end
+print()
+
+local list = table.create(base)
+for i = 1, base do list[i] = {} end
+local cnt = size * base
+local n = zero
+while cnt > 0 do
+    local mpdr = mult_digital_root(n, base)
+    local mdr = mpdr[2]
+    if #list[mdr + 1] < size then
+        list[mdr + 1]:insert(n)
+        cnt -= 1
+    end
+    n += one
+end
+fmt.print("%3s: %s", "MDR", "First")
+local i = 0
+for list as l do
+    fmt.print("%3d: %,s", i, l)
+    i += 1
+end