Merge branch 'master' into Swift4-updates

Author: bobdel

.travis.yml

@@ -1,5 +1,5 @@
 language: objective-c
-osx_image: xcode8.3
+osx_image: xcode9
 # sudo: false
 
 install:

Array2D/Array2D.playground/Contents.swift

@@ -1,3 +1,8 @@
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 /*
  Two-dimensional array with a fixed number of rows and columns.
  This is mostly handy for games that are played on a grid, such as chess.

Breadth-First Search/BreadthFirstSearch.playground/Pages/Simple example.xcplaygroundpage/Contents.swift

@@ -1,3 +1,8 @@
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 func breadthFirstSearch(_ graph: Graph, source: Node) -> [String] {
   var queue = Queue<Node>()
   queue.enqueue(source)

Depth-First Search/DepthFirstSearch.playground/Pages/Simple Example.xcplaygroundpage/Contents.swift

@@ -1,3 +1,8 @@
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 func depthFirstSearch(_ graph: Graph, source: Node) -> [String] {
   var nodesExplored = [source.label]
   source.visited = true

Linear Search/LinearSearch.playground/Contents.swift

@@ -6,10 +6,10 @@ print("Hello, Swift 4!")
 #endif
 
 func linearSearch<T: Equatable>(_ array: [T], _ object: T) -> Int? {
-  for (index, obj) in array.enumerated() where obj == object {
-    return index
-  }
-  return nil
+    for (index, obj) in array.enumerated() where obj == object {
+        return index
+    }
+    return nil
 }
 
 let array = [5, 2, 4, 7]

Selection Sort/SelectionSort.playground/Contents.swift

@@ -1,21 +1,9 @@
 //: Playground - noun: a place where people can play
 
-func selectionSort<T>(_ array: [T], _ isOrderedBefore: (T, T) -> Bool) -> [T] {
-  guard array.count > 1 else { return array }
-  var a = array
-  for x in 0 ..< a.count - 1 {
-    var lowest = x
-    for y in x + 1 ..< a.count {
-      if isOrderedBefore(a[y], a[lowest]) {
-        lowest = y
-      }
-    }
-    if x != lowest {
-      swap(&a[x], &a[lowest])
-    }
-  }
-  return a
-}
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
 
 let list = [ 10, -1, 3, 9, 2, 27, 8, 5, 1, 3, 0, 26 ]
 selectionSort(list, <)

Selection Sort/SelectionSort.playground/Sources/SelectionSort.swift

@@ -0,0 +1,21 @@
+public func selectionSort<T: Comparable>(_ array: [T], _ isOrderedBefore: (T, T) -> Bool) -> [T] {
+  guard array.count > 1 else { return array }
+
+  var a = array
+  for x in 0 ..< a.count - 1 {
+
+    // Find the lowest value in the rest of the array.
+    var lowest = x
+    for y in x + 1 ..< a.count {
+      if isOrderedBefore(a[y], a[lowest]) {
+        lowest = y
+      }
+    }
+
+    // Swap the lowest value with the current array index.
+    if x != lowest {
+      a.swapAt(x, lowest)
+    }
+  }
+  return a
+}

Selection Sort/SelectionSort.playground/timeline.xctimeline

@@ -1,21 +1,21 @@
-func selectionSort<T>(_ array: [T], _ isOrderedBefore: (T, T) -> Bool) -> [T] {
-  guard array.count > 1 else { return array }
+public func selectionSort<T: Comparable>(_ array: [T], _ isOrderedBefore: (T, T) -> Bool) -> [T] {
+    guard array.count > 1 else { return array }
 
-  var a = array
-  for x in 0 ..< a.count - 1 {
+    var a = array
+    for x in 0 ..< a.count - 1 {
 
-    // Find the lowest value in the rest of the array.
-    var lowest = x
-    for y in x + 1 ..< a.count {
-      if isOrderedBefore(a[y], a[lowest]) {
-        lowest = y
-      }
-    }
+        // Find the lowest value in the rest of the array.
+        var lowest = x
+        for y in x + 1 ..< a.count {
+            if isOrderedBefore(a[y], a[lowest]) {
+                lowest = y
+            }
+        }
 
-    // Swap the lowest value with the current array index.
-    if x != lowest {
-      swap(&a[x], &a[lowest])
+        // Swap the lowest value with the current array index.
+        if x != lowest {
+            a.swapAt(x, lowest)
+        }
     }
-  }
-  return a
+    return a
 }

Selection Sort/SelectionSort.swift

@@ -1,40 +1,15 @@
 //: Playground - noun: a place where people can play
 
-import Foundation
-
-/* Returns a random integer between 0 and n-1. */
-public func random(_ n: Int) -> Int {
-  return Int(arc4random_uniform(UInt32(n)))
-}
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
 
-/* Fisher-Yates / Knuth shuffle */
-extension Array {
-  public mutating func shuffle() {
-    for i in stride(from: count - 1, through: 1, by: -1) {
-      let j = random(i + 1)
-      if i != j {
-        swap(&self[i], &self[j])
-      }
-    }
-  }
-}
+import Foundation
 
 var list = [ "a", "b", "c", "d", "e", "f", "g" ]
 list.shuffle()
 list.shuffle()
 list.shuffle()
 
-/* Create a new array of numbers that is already shuffled. */
-public func shuffledArray(_ n: Int) -> [Int] {
-  var a = [Int](repeating: 0, count: n)
-  for i in 0..<n {
-    let j = random(i + 1)
-    if i != j {
-      a[i] = a[j]
-    }
-    a[j] = i
-  }
-  return a
-}
-
 let numbers = shuffledArray(10)