Updated MST (Unweighted) to Swift 4.2

Author: inickt

Minimum Spanning Tree (Unweighted)/MinimumSpanningTree.playground/Pages/Minimum spanning tree example.xcplaygroundpage/Contents.swift

@@ -1,8 +1,3 @@
-// last checked with Xcode 9.0b4
-#if swift(>=4.0)
-print("Hello, Swift 4!")
-#endif
-
 func breadthFirstSearchMinimumSpanningTree(_ graph: Graph, source: Node) -> Graph {
   let minimumSpanningTree = graph.duplicate()
 

Minimum Spanning Tree (Unweighted)/MinimumSpanningTree.playground/playground.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>