From d068f0b3c11348a50c18af1ee3b0d2e5f38c4faf Mon Sep 17 00:00:00 2001
From: Matthew Sotoudeh <matthew@masot.net>
Date: Fri, 17 May 2024 15:57:30 -0700
Subject: lua benchmarks

---
 .../tests/Lua-Benchmarks/fannkuch-redux.lua        | 49 ++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 lua_benchmark/tests/Lua-Benchmarks/fannkuch-redux.lua

(limited to 'lua_benchmark/tests/Lua-Benchmarks/fannkuch-redux.lua')

diff --git a/lua_benchmark/tests/Lua-Benchmarks/fannkuch-redux.lua b/lua_benchmark/tests/Lua-Benchmarks/fannkuch-redux.lua
new file mode 100644
index 0000000..51f5fc6
--- /dev/null
+++ b/lua_benchmark/tests/Lua-Benchmarks/fannkuch-redux.lua
@@ -0,0 +1,49 @@
+-- The Computer Language Benchmarks Game
+-- http://benchmarksgame.alioth.debian.org/
+-- contributed by Mike Pall
+
+local function fannkuch(n)
+  local p, q, s, sign, maxflips, sum = {}, {}, {}, 1, 0, 0
+  for i=1,n do p[i] = i; q[i] = i; s[i] = i end
+  repeat
+    -- Copy and flip.
+    local q1 = p[1]				-- Cache 1st element.
+    if q1 ~= 1 then
+      for i=2,n do q[i] = p[i] end		-- Work on a copy.
+      local flips = 1
+      repeat
+	local qq = q[q1]
+	if qq == 1 then				-- ... until 1st element is 1.
+	  sum = sum + sign*flips
+	  if flips > maxflips then maxflips = flips end -- New maximum?
+	  break
+	end
+	q[q1] = q1
+	if q1 >= 4 then
+	  local i, j = 2, q1 - 1
+	  repeat q[i], q[j] = q[j], q[i]; i = i + 1; j = j - 1; until i >= j
+	end
+	q1 = qq; flips = flips + 1
+      until false
+    end
+    -- Permute.
+    if sign == 1 then
+      p[2], p[1] = p[1], p[2]; sign = -1	-- Rotate 1<-2.
+    else
+      p[2], p[3] = p[3], p[2]; sign = 1		-- Rotate 1<-2 and 1<-2<-3.
+      for i=3,n do
+	local sx = s[i]
+	if sx ~= 1 then s[i] = sx-1; break end
+	if i == n then return sum, maxflips end	-- Out of permutations.
+	s[i] = i
+	-- Rotate 1<-...<-i+1.
+	local t = p[1]; for j=1,i do p[j] = p[j+1] end; p[i+1] = t
+      end
+    end
+  until false
+end
+
+-- local n = tonumber(arg and arg[1]) or 7
+local n = 10
+local sum, flips = fannkuch(n)
+io.write(sum, "\nPfannkuchen(", n, ") = ", flips, "\n")
-- 
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