1 files changed, 46 insertions, 0 deletions
diff --git a/lua_benchmark/tests/Lua-Benchmarks/queen.lua b/lua_benchmark/tests/Lua-Benchmarks/queen.lua
new file mode 100644
index 0000000..9071406
--- /dev/null
+++ b/lua_benchmark/tests/Lua-Benchmarks/queen.lua
@@ -0,0 +1,46 @@
+local N = tonumber(arg[1] or 8)    -- board size
+
+
+-- check whether position (n,c) is free from attacks
+local function isplaceok (a, n, c)
+  for i = 1, n - 1 do   -- for each queen already placed
+    if (a[i] == c) or                -- same column?
+       (a[i] - i == c - n) or        -- same diagonal?
+       (a[i] + i == c + n) then      -- same diagonal?
+      return false            -- place can be attacked
+    end
+  end
+  return true    -- no attacks; place is OK
+end
+
+
+-- print a board
+local function printsolution (a)
+  for i = 1, N do
+    for j = 1, N do
+      io.write(a[i] == j and "X" or "-", " ")
+    end
+    io.write("\n")
+  end
+  io.write("\n")
+end
+
+
+-- add to board 'a' all queens from 'n' to 'N'
+local function addqueen (a, n)
+  if n > N then    -- all queens have been placed?
+    printsolution(a)
+  else  -- try to place n-th queen
+    for c = 1, N do
+      if isplaceok(a, n, c) then
+        a[n] = c    -- place n-th queen at column 'c'
+        addqueen(a, n + 1)
+      end
+    end
+  end
+end
+
+
+-- run the program
+addqueen({}, 1)
+