Week 148, part 2: Lua solution

1 files changed, 109 insertions, 0 deletions

diff --git a/challenge-148/abigail/lua/ch-2.lua b/challenge-148/abigail/lua/ch-2.lua
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+++ b/challenge-148/abigail/lua/ch-2.lua
@@ -0,0 +1,109 @@
+#!/opt/local/bin/lua
+
+--
+-- See https://theweeklychallenge.org/blog/perl-weekly-challenge-148
+--
+
+--
+-- Run as: lua ch-2.lua
+--
+
+local COUNT = 5
+local A     = 0
+local B     = 1
+local C     = 2
+local SUM   = 3
+local out   = {}
+for i = 1, COUNT do
+    out [i] = {}
+    out [i] [A]   = 999999
+    out [i] [B]   = 999999
+    out [i] [C]   = 999999
+    out [i] [SUM] = out [i] [A] + out [i] [B] + out [i] [C]
+end
+
+local k         = 0
+local max_index = 1
+
+while 3 * k + 2 <= out [max_index] [SUM] do
+    local a  = 3 * k + 2
+    local f1 =     k + 1
+    local f2 = 8 * k + 5
+
+    --
+    -- Find divisors of f1
+    --
+    local d1 = {}
+    local i = 0
+    while i * i <= f1 do
+        if f1 % i == 0 then
+            d1 [#d1 + 1] = i
+            if f1 / i ~= i then
+                d1 [#d1 + 1] = f1 / i
+            end
+        end
+        i = i + 1
+    end
+
+    local d2 = {}
+    i = 0
+    while i * i <= f2 do
+        if f2 % i == 0 then
+            local s1 = math . floor (math . sqrt (i))
+            local s2 = math . floor (math . sqrt (f2 / i))
+            if s1 * s1 == i then
+                d2 [#d2 + 1] = s1
+            end
+            if s2 * s2 == f2 / i and s1 ~= s2 then
+                d2 [#d2 + 1] = s2
+            end
+        end
+        i = i + 1
+    end
+
+    local d1v
+    local d2v
+
+    for _, d1v in ipairs (d1) do
+        for _, d2v in ipairs (d2) do
+            local b = d1v * d2v
+            local c = f1 * f1 * f2 / (b * b)
+            if (a + b + c) < out [max_index] [SUM] then
+                local i
+                for i = 1, COUNT do
+                    if out [i] [A] == a and out [i] [B] == b then
+                        goto end_loop
+                    end
+                end
+
+                out [max_index] [A]   = a
+                out [max_index] [B]   = b
+                out [max_index] [C]   = c
+                out [max_index] [SUM] = a + b + c
+
+                --
+                -- Find new max_index
+                --
+
+                max_index = 1
+                local max_sum = out [max_index] [SUM]
+
+                local l
+                for l = 2, COUNT do
+                    if max_sum < out [l] [SUM] then
+                        max_index = l
+                        max_sum   = out [l] [SUM]
+                    end
+                end
+            end
+            ::end_loop::
+        end
+    end
+
+    k = k + 1
+end
+
+for i = 1, COUNT do
+    print (out [i] [A] .. " " .. out [i] [B] .. " " .. out [i] [C])
+end
+