Merge pull request kodecocodes#613 from remlostime/dijkstra-swift

[Swift 4] Update Dijkstra

Author: kelvinlauKL

Dijkstra Algorithm/Dijkstra.playground/Contents.swift

@@ -1,6 +1,11 @@
 //: Playground - noun: a place where people can play
 import Foundation
 
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 var vertices: Set<Vertex> = Set()
 
 func createNotConnectedVertices() {

Dijkstra Algorithm/VisualizedDijkstra.playground/Contents.swift

@@ -8,6 +8,12 @@
  */
 import UIKit
 import PlaygroundSupport
+
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 /*:
  First of all, let's set up colors for our window and graph. The visited color will be applied to visited vertices. The checking color will be applied to an edge and an edge neighbor every time the algorithm is checking some vertex neighbors. And default colors are just initial colors for elements.
  */