Data commit

Task/Power-set/Lua/power-set.lua

@@ -0,0 +1,33 @@
+--returns the powerset of s, out of order.
+function powerset(s, start)
+  start = start or 1
+  if(start > #s) then return {{}} end
+  local ret = powerset(s, start + 1)
+  for i = 1, #ret do
+    ret[#ret + 1] = {s[start], unpack(ret[i])}
+  end
+  return ret
+end
+
+--non-recurse implementation
+function powerset(s)
+   local t = {{}}
+   for i = 1, #s do
+      for j = 1, #t do
+         t[#t+1] = {s[i],unpack(t[j])}
+      end
+   end
+   return t
+end
+
+--alternative, copied from the Python implementation
+function powerset2(s)
+  local ret = {{}}
+  for i = 1, #s do
+    local k = #ret
+    for j = 1, k do
+      ret[k + j] = {s[i], unpack(ret[j])}
+    end
+  end
+  return ret
+end