Merge pull request #2 from raywenderlich/master

update

Author: tangzzz-fan

.travis.yml

@@ -124,9 +124,8 @@ Below are some examples for each category of performance:
   func solveHanoi(n: Int, from: String, to: String, spare: String) {
     guard n >= 1 else { return }
     if n > 1 {
-      solveHanoi(n: n - 1, from: from, to: spare, spare: to)
-    } else {
-      solveHanoi(n: n - 1, from: spare, to: to, spare: from)
+        solveHanoi(n: n - 1, from: from, to: spare, spare: to)
+        solveHanoi(n: n - 1, from: spare, to: to, spare: from)
     }
   }
   ```

Big-O Notation.markdown

@@ -212,7 +212,7 @@ extension Heap where T: Equatable {
     return nodes.index(where: { $0 == node })
   }
 
-  /** Removes the first occurrence of a node from the heap. Performance: O(n log n). */
+  /** Removes the first occurrence of a node from the heap. Performance: O(n). */
   @discardableResult public mutating func remove(node: T) -> T? {
     if let index = index(of: node) {
       return remove(at: index)

Heap/Heap.swift

@@ -23,7 +23,7 @@ public struct Queue<T> {
   }
 
   public mutating func dequeue() -> T? {
-    guard head < array.count, let element = array[head] else { return nil }
+    guard let element = array[guarded: head] else { return nil }
 
     array[head] = nil
     head += 1
@@ -45,3 +45,12 @@ public struct Queue<T> {
     }
   }
 }
+
+extension Array {
+    subscript(guarded idx: Int) -> Element? {
+        guard (startIndex..<endIndex).contains(idx) else {
+            return nil
+        }
+        return self[idx]
+    }
+}

Queue/Queue-Optimized.swift

@@ -42,12 +42,12 @@ func partitionLomuto<T: Comparable>(_ a: inout [T], low: Int, high: Int) -> Int
   var i = low
   for j in low..<high {
     if a[j] <= pivot {
-      (a[i], a[j]) = (a[j], a[i])
+      a.swapAt(i, j)
       i += 1
     }
   }
 
-  (a[i], a[high]) = (a[high], a[i])
+  a.swapAt(i, high)
   return i
 }
 

Quicksort/Quicksort.playground/Contents.swift

@@ -137,12 +137,12 @@ func partitionLomuto<T: Comparable>(_ a: inout [T], low: Int, high: Int) -> Int
   var i = low
   for j in low..<high {
     if a[j] <= pivot {
-      (a[i], a[j]) = (a[j], a[i])
+	  a.swapAt(i, j)
       i += 1
     }
   }
 
-  (a[i], a[high]) = (a[high], a[i])
+  a.swapAt(i, high)
   return i
 }
 ```

Quicksort/README.markdown

@@ -138,7 +138,7 @@ extension Tour {
   }
 
   func shuffle() {
-    self.shuffle()
+    self.tour.shuffle()
   }
 }
 

Simulated annealing/simann_example.swift

@@ -5,3 +5,16 @@ print("Hello, Swift 4!")
 
 // SkipList is ready for Swift 4.
 // TODO: Add Test
+
+let k = SkipList<Int, String>()
+k.insert(key: 10, data: "10")
+k.insert(key: 12, data: "12")
+k.insert(key: 13, data: "13")
+k.insert(key: 20, data: "20")
+k.insert(key: 24, data: "24")
+
+if let value = k.get(key: 20) {
+  print(value)
+} else {
+  print("not found!")
+}

Skip-List/SkipList.playground/Contents.swift

@@ -212,7 +212,7 @@ extension SkipList {
     }
   }
 
-  func insert(key: Key, data: Payload) {
+  public func insert(key: Key, data: Payload) {
     if head != nil {
       if let node = findNode(key: key) {
         // replace, in case of key already exists.

Skip-List/SkipList.playground/Sources/SkipList.swift

@@ -212,7 +212,7 @@ extension SkipList {
     }
   }
 
-  func insert(key: Key, data: Payload) {
+  public func insert(key: Key, data: Payload) {
     if head != nil {
       if let node = findNode(key: key) {
         // replace, in case of key already exists.