Merge pull request #5533 from Abigail/abigail/week-147

Abigail/week 147

1 files changed, 57 insertions, 0 deletions

diff --git a/challenge-147/abigail/lua/ch-1.lua b/challenge-147/abigail/lua/ch-1.lua
new file mode 100644
index 0000000000..0c86152ba1
--- /dev/null
+++ b/challenge-147/abigail/lua/ch-1.lua
@@ -0,0 +1,57 @@
+#!/opt/local/bin/lua
+
+--
+-- See https://theweeklychallenge.org/blog/perl-weekly-challenge-147
+--
+
+--
+-- Run as: lua ch-1.lua
+--
+
+function is_prime (p)
+    if p == 2 then
+        return true
+    end
+    if p % 2 == 0 then
+        return false
+    end
+    i = 3
+    while i * i <= p do
+        if p % i == 0 then
+            return false
+        end
+        i = i + 2
+    end
+    return true
+end
+
+todo = {2, 3, 5, 7}
+for i, p in ipairs (todo) do
+    io . write (p, " ")
+end
+
+count = 20 - #todo
+
+pow = 10
+while #todo > 0 do
+    new_todo = {}
+    for d = 1, 9 do
+        for i, p in ipairs (todo) do
+            candidate = d * pow + p
+            if is_prime (candidate) then
+                io . write (candidate, " ")
+                new_todo [#new_todo + 1] = candidate
+                count = count - 1
+                if count <= 0 then
+                    goto end_of_while
+                end
+            end
+        end
+    end
+    todo = new_todo
+    pow  = pow * 10
+end
+
+::end_of_while::
+
+io . write ("\n")