Data commit

Task/Sorting-algorithms-Permutation-sort/Lua/sorting-algorithms-permutation-sort.lua

@@ -0,0 +1,30 @@
+-- Return an iterator to produce every permutation of list
+function permute (list)
+  local function perm (list, n)
+    if n == 0 then coroutine.yield(list) end
+    for i = 1, n do
+      list[i], list[n] = list[n], list[i]
+      perm(list, n - 1)
+      list[i], list[n] = list[n], list[i]
+    end
+  end
+  return coroutine.wrap(function() perm(list, #list) end)
+end
+
+-- Return true if table t is in ascending order or false if not
+function inOrder (t)
+  for pos = 2, #t do
+    if t[pos] < t[pos - 1] then
+      return false
+    end
+  end
+  return true
+end
+
+-- Main procedure
+local list = {2,3,1}                 --\   Written to match task pseudocode,
+local nextPermutation = permute(list) --\  more idiomatic would be:
+while not inOrder(list) do             --\
+  list = nextPermutation()             --/   for p in permute(list) do
+end                                   --/       stuffWith(p)
+print(unpack(list))                  --/     end