[Swift 4] Update Selection Sort

Author: remlostime

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
 }