Merge pull request #232 from JaapWijnen/update-ordered-array

Update Ordered Array to Swift 3

Author: kelvinlauKL

Ordered Array/OrderedArray.playground/Contents.swift

@@ -1,10 +1,10 @@
 //: Playground - noun: a place where people can play
 
 public struct OrderedArray<T: Comparable> {
-  private var array = [T]()
+  fileprivate var array = [T]()
 
   public init(array: [T]) {
-    self.array = array.sort()
+    self.array = array.sorted()
   }
 
   public var isEmpty: Bool {
@@ -20,16 +20,16 @@ public struct OrderedArray<T: Comparable> {
   }
 
   public mutating func removeAtIndex(index: Int) -> T {
-    return array.removeAtIndex(index)
+    return array.remove(at: index)
   }
 
   public mutating func removeAll() {
     array.removeAll()
   }
 
-  public mutating func insert(newElement: T) -> Int {
+  public mutating func insert(_ newElement: T) -> Int {
     let i = findInsertionPoint(newElement)
-    array.insert(newElement, atIndex: i)
+    array.insert(newElement, at: i)
     return i
   }
 
@@ -46,19 +46,21 @@ public struct OrderedArray<T: Comparable> {
   */
 
   // Fast version that uses a binary search.
-  private func findInsertionPoint(newElement: T) -> Int {
-    var range = 0..<array.count
-    while range.startIndex < range.endIndex {
-      let midIndex = range.startIndex + (range.endIndex - range.startIndex) / 2
-      if array[midIndex] == newElement {
-        return midIndex
-      } else if array[midIndex] < newElement {
-        range.startIndex = midIndex + 1
-      } else {
-        range.endIndex = midIndex
-      }
+  private func findInsertionPoint(_ newElement: T) -> Int {
+    var startIndex = 0
+    var endIndex = array.count
+    
+    while startIndex < endIndex {
+        let midIndex = startIndex + (endIndex - startIndex) / 2
+        if array[midIndex] == newElement {
+            return midIndex
+        } else if array[midIndex] < newElement {
+            startIndex = midIndex + 1
+        } else {
+            endIndex = midIndex
+        }
     }
-    return range.startIndex
+    return startIndex
   }
 }
 

Ordered Array/README.markdown

@@ -8,28 +8,28 @@ The implementation is quite basic. It's simply a wrapper around Swift's built-in
 
 ```swift
 public struct OrderedArray<T: Comparable> {
-  private var array = [T]()
-  
+  fileprivate var array = [T]()
+
   public init(array: [T]) {
-    self.array = array.sort()
+    self.array = array.sorted()
   }
 
   public var isEmpty: Bool {
     return array.isEmpty
   }
-  
+
   public var count: Int {
     return array.count
   }
-  
+
   public subscript(index: Int) -> T {
     return array[index]
   }
-  
+
   public mutating func removeAtIndex(index: Int) -> T {
-    return array.removeAtIndex(index)
+    return array.remove(at: index)
   }
-  
+
   public mutating func removeAll() {
     array.removeAll()
   }
@@ -47,13 +47,13 @@ As you can see, all these methods simply call the corresponding method on the in
 What remains is the `insert()` function. Here is an initial stab at it:
 
 ```swift
-  public mutating func insert(newElement: T) -> Int {
+  public mutating func insert(_ newElement: T) -> Int {
     let i = findInsertionPoint(newElement)
-    array.insert(newElement, atIndex: i)
+    array.insert(newElement, at: i)
     return i
   }
 
-  private func findInsertionPoint(newElement: T) -> Int {
+  private func findInsertionPoint(_ newElement: T) -> Int {
     for i in 0..<array.count {
       if newElement <= array[i] {
         return i
@@ -63,7 +63,7 @@ What remains is the `insert()` function. Here is an initial stab at it:
   }
 ```
 
-The helper function `findInsertionPoint()` simply iterates through the entire array, looking for the right place to insert the new element. 
+The helper function `findInsertionPoint()` simply iterates through the entire array, looking for the right place to insert the new element.
 
 > **Note:** Quite conveniently, `array.insert(... atIndex: array.count)` adds the new object to the end of the array, so if no suitable insertion point was found we can simply return `array.count` as the index.
 
@@ -81,26 +81,28 @@ a.insert(10)   // inserted at index 8
 a              // [-2, -1, 1, 3, 4, 5, 7, 9, 10]
 ```
 
-The array's contents will always be sorted from low to high, now matter what. 
+The array's contents will always be sorted from low to high, now matter what.
 
 Unfortunately, the current `findInsertionPoint()` function is a bit slow. In the worst case, it needs to scan through the entire array. We can speed this up by using a [binary search](../Binary Search) to find the insertion point.
 
 Here is the new version:
 
 ```swift
-  private func findInsertionPoint(newElement: T) -> Int {
-    var range = 0..<array.count
-    while range.startIndex < range.endIndex {
-      let midIndex = range.startIndex + (range.endIndex - range.startIndex) / 2
-      if array[midIndex] == newElement {
-        return midIndex
-      } else if array[midIndex] < newElement {
-        range.startIndex = midIndex + 1
-      } else {
-        range.endIndex = midIndex
-      }
+  private func findInsertionPoint(_ newElement: T) -> Int {
+    var startIndex = 0
+    var endIndex = array.count
+
+    while startIndex < endIndex {
+        let midIndex = startIndex + (endIndex - startIndex) / 2
+        if array[midIndex] == newElement {
+            return midIndex
+        } else if array[midIndex] < newElement {
+            startIndex = midIndex + 1
+        } else {
+            endIndex = midIndex
+        }
     }
-    return range.startIndex
+    return startIndex
   }
 ```