Initial data commit

Task/Power-set/Nim/power-set.nim

@@ -0,0 +1,17 @@
+import sets, hashes
+
+proc hash(x: HashSet[int]): Hash =
+  var h = 0
+  for i in x: h = h !& hash(i)
+  result = !$h
+
+proc powerset[T](inset: HashSet[T]): HashSet[HashSet[T]] =
+  result.incl(initHashSet[T]())  # Initialized with empty set.
+  for val in inset:
+    let previous = result
+    for aSet in previous:
+      var newSet = aSet
+      newSet.incl(val)
+      result.incl(newSet)
+
+echo powerset([1,2,3,4].toHashSet())