Merge pull request kodecocodes#523 from remlostime/union-find

[Swift 4] Update Union Find

Author: vincentngo

Union-Find/UnionFind.playground/Contents.swift

@@ -1,5 +1,10 @@
 //: Playground - noun: a place where people can play
 
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 var dsu = UnionFindQuickUnion<Int>()
 
 for i in 1...10 {