Merge pull request wokalski#48 from farzadshbfn/master

Fixes #46. Stack overflow crash.

Author: wokalski

Sources/LinkedList.swift

@@ -9,17 +9,32 @@ class LinkedList<T> {
     }
 
     init?(array: [T]) {
+        let reversed = array.reversed()
         guard let first = array.first else {
             return nil
         }
-        self.next = LinkedList(array: Array(array.dropFirst()))
+
+        var tailLinkedList: LinkedList?
+
+        for i in 0 ..< reversed.count - 1 {
+            tailLinkedList = LinkedList(next: tailLinkedList, value: reversed.itemOnStartIndex(advancedBy: i))
+        }
+
+        self.next = tailLinkedList
         self.value = first
     }
+
+    func array() -> Array<T> {
+        if let next = next {
+            return [value] + next.array()
+        }
+        return [value]
+    }
 }
 
 class DoublyLinkedList<T> {
     let next: DoublyLinkedList?
-    private(set) var previous: DoublyLinkedList? = nil
+    private(set) var previous: DoublyLinkedList?
     var head: DoublyLinkedList {
         guard let previous = previous else {
             return self
@@ -29,16 +44,38 @@ class DoublyLinkedList<T> {
 
     var value: T
 
-    init?(linkedList: LinkedList<T>?) {
-        guard let element = linkedList else {
+    init(next: DoublyLinkedList?, value: T) {
+        self.value = value
+        self.next = next
+        self.next?.previous = self
+    }
+
+    init?(array: [T]) {
+        let reversed = array.reversed()
+        guard let first = array.first else {
             return nil
         }
 
-        self.value = element.value
-        self.next = DoublyLinkedList(linkedList: element.next)
+        var tailDoublyLinkedList: DoublyLinkedList?
+
+        for i in 0 ..< reversed.count - 1 {
+            let nextTail = DoublyLinkedList(next: tailDoublyLinkedList, value: reversed.itemOnStartIndex(advancedBy: i))
+            tailDoublyLinkedList?.previous = nextTail
+            tailDoublyLinkedList = nextTail
+        }
+
+        self.value = first
+        self.next = tailDoublyLinkedList
         self.next?.previous = self
     }
 
+    convenience init?(linkedList: LinkedList<T>?) {
+        guard let linkedList = linkedList else {
+            return nil
+        }
+        self.init(array: linkedList.array())
+    }
+
     func array() -> Array<T> {
         if let next = next {
             return [value] + next.array()