1 class MyCircularDeque {
 2     var data:[Int] 
 3     var size:Int
 4 
 5     /** Initialize your data structure here. Set the size of the deque to be k. */
 6     init(_ k: Int) {
 7         data = [Int]()
 8         size = k
 9     }
10     
11     /** Adds an item at the front of Deque. Return true if the operation is successful. */
12     func insertFront(_ value: Int) -> Bool {
13         if isFull() {return false}
14         data.insert(value,at:0)
15         return true      
16     }
17     
18     /** Adds an item at the rear of Deque. Return true if the operation is successful. */
19     func insertLast(_ value: Int) -> Bool {
20         if isFull() {return false}
21         data.append(value)
22         return true      
23     }
24     
25     /** Deletes an item from the front of Deque. Return true if the operation is successful. */
26     func deleteFront() -> Bool {
27         if isEmpty() {return false}
28         data.removeFirst()
29         return true      
30     }
31     
32     /** Deletes an item from the rear of Deque. Return true if the operation is successful. */
33     func deleteLast() -> Bool {
34         if isEmpty() {return false}
35         data.popLast()
36         return true
37     }
38     
39     /** Get the front item from the deque. */
40     func getFront() -> Int {
41         if isEmpty() {return -1}
42         return data.first!
43       
44     }
45     
46     /** Get the last item from the deque. */
47     func getRear() -> Int {
48         if isEmpty() {return -1}
49         return data.last!
50     }
51     
52     /** Checks whether the circular deque is empty or not. */
53     func isEmpty() -> Bool {
54         return data.isEmpty      
55     }
56     
57     /** Checks whether the circular deque is full or not. */
58     func isFull() -> Bool {
59         return data.count >= size      
60     }
61 }
62 
63 /**
64  * Your MyCircularDeque object will be instantiated and called as such:
65  * let obj = MyCircularDeque(k)
66  * let ret_1: Bool = obj.insertFront(value)
67  * let ret_2: Bool = obj.insertLast(value)
68  * let ret_3: Bool = obj.deleteFront()
69  * let ret_4: Bool = obj.deleteLast()
70  * let ret_5: Int = obj.getFront()
71  * let ret_6: Int = obj.getRear()
72  * let ret_7: Bool = obj.isEmpty()
73  * let ret_8: Bool = obj.isFull()
74  */ 

  1 class MyCircularDeque: CustomStringConvertible {
  2     
  3     var capacity: Int {
  4         return deque.count
  5     }
  6     
  7     var description: String {
  8         return deque.description
  9     }
 10     
 11     private var deque: [Int]
 12     
 13     private var frontIndex: Int?
 14     private var rearIndex: Int?
 15     
 16     /** Initialize your data structure here. Set the size of the deque to be k. */
 17     init(_ k: Int) {
 18         self.deque = [Int].init(repeating: 0, count: k)
 19     }
 20     
 21     /** Adds an item at the front of Deque. Return true if the operation is successful. */
 22     func insertFront(_ value: Int) -> Bool {
 23         guard isFull() == false else {
 24             return false
 25         }
 26         
 27         if var front = self.frontIndex {
 28             front = shiftBackwards(front)
 29             self.frontIndex = front
 30             deque[front] = value
 31             
 32         } else {
 33             self.frontIndex = 0
 34             self.rearIndex = 0
 35             deque[0] = value
 36         }
 37         
 38         return true
 39     }
 40     
 41     /** Adds an item at the rear of Deque. Return true if the operation is successful. */
 42     func insertLast(_ value: Int) -> Bool {
 43         guard isFull() == false else {
 44             return false
 45         }
 46         
 47         if var rear = self.rearIndex {
 48             rear = shiftForwards(rear)
 49             self.rearIndex = rear
 50             deque[rear] = value
 51             
 52         } else {
 53             self.frontIndex = 0
 54             self.rearIndex = 0
 55             deque[0] = value
 56         }
 57         
 58         return true
 59     }
 60     
 61     /** Deletes an item from the front of Deque. Return true if the operation is successful. */
 62     func deleteFront() -> Bool {
 63         guard isEmpty() == false else {
 64             return false
 65         }
 66         
 67         guard let front = self.frontIndex else {
 68             fatalError("front must be valid in a non empty deque")
 69         }
 70         
 71         if front == self.rearIndex {
 72             self.frontIndex = nil
 73             self.rearIndex = nil
 74         } else {
 75             self.frontIndex = shiftForwards(front)
 76         }
 77         
 78         return true
 79     }
 80     
 81     /** Deletes an item from the rear of Deque. Return true if the operation is successful. */
 82     func deleteLast() -> Bool {
 83         guard isEmpty() == false else {
 84             return false
 85         }
 86         
 87         guard let rear = self.rearIndex else {
 88             fatalError("rear must be valid in a non empty deque")
 89         }
 90         
 91         if rear == self.frontIndex {
 92             self.frontIndex = nil
 93             self.rearIndex = nil
 94         } else {
 95             self.rearIndex = shiftBackwards(rear)
 96         }
 97         
 98         return true
 99     }
100     
101     /** Get the front item from the deque. */
102     func getFront() -> Int {
103         guard let front = self.frontIndex else {
104             return -1
105         }
106         
107         return self.deque[front]
108     }
109     
110     /** Get the last item from the deque. */
111     func getRear() -> Int {
112         guard let rear = self.rearIndex else {
113             return -1
114         }
115         
116         return self.deque[rear]
117     }
118     
119     /** Checks whether the circular deque is empty or not. */
120     func isEmpty() -> Bool {
121         return self.frontIndex == nil && self.rearIndex == nil
122     }
123     
124     /** Checks whether the circular deque is full or not. */
125     func isFull() -> Bool {
126         if let front = self.frontIndex, let rear = self.rearIndex {
127             
128             if rear < front, front == shiftForwards(rear) {
129                 return true
130             }
131             
132             if rear > front, front == 0, rear == self.capacity - 1 {
133                 return true
134             }
135         }
136         
137         return false
138     }
139     
140     private func shiftForwards(_ i: Int) -> Int {
141         var index = i + 1
142         if index == capacity {
143             index = 0
144         }
145         
146         return index
147     }
148     
149     private func shiftBackwards(_ i: Int) -> Int {
150         var index = i - 1
151         if index == -1 {
152             index = capacity - 1
153         }
154         
155         return index
156     }
157 }

  1 class MyCircularDeque {
  2     private class Node {
  3         public var prev: Node?
  4         public var next: Node?
  5         public var val: Int
  6         
  7         init(_ val: Int) {
  8             self.val = val
  9         }
 10     }
 11     
 12     private var head: Node?
 13     private var tail: Node?
 14     private var maxSize: Int
 15     private var size: Int
 16 
 17     /** Initialize your data structure here. Set the size of the deque to be k. */
 18     init(_ k: Int) {
 19         self.maxSize = k
 20         self.size = 0
 21     }
 22     
 23     /** Adds an item at the front of Deque. Return true if the operation is successful. */
 24     func insertFront(_ value: Int) -> Bool {
 25         guard self.size < self.maxSize else {
 26             return false
 27         }
 28         
 29         let node = Node(value)
 30         node.prev = self.head
 31         self.head?.next = node
 32         self.head = node
 33         if size == 0 {
 34             self.tail = node
 35         }
 36         self.size += 1
 37         
 38         return true
 39     }
 40     
 41     /** Adds an item at the rear of Deque. Return true if the operation is successful. */
 42     func insertLast(_ value: Int) -> Bool {
 43         guard self.size < self.maxSize else {
 44             return false
 45         }
 46         
 47         let node = Node(value)
 48         node.next = self.tail
 49         self.tail?.prev = node
 50         self.tail = node
 51         if size == 0 {
 52             self.head = node
 53         }
 54         self.size += 1
 55         
 56         return true
 57     }
 58     
 59     /** Deletes an item from the front of Deque. Return true if the operation is successful. */
 60     func deleteFront() -> Bool {
 61         guard self.size > 0 else {
 62             return false
 63         }
 64 
 65         self.head = self.head?.prev
 66         self.head?.next = nil
 67         self.size -= 1
 68         if self.size == 0 {
 69             self.head = nil
 70             self.tail = nil
 71         }
 72         
 73         return true
 74     }
 75     
 76     /** Deletes an item from the rear of Deque. Return true if the operation is successful. */
 77     func deleteLast() -> Bool {
 78         guard self.size > 0 else {
 79             return false
 80         }
 81         
 82         self.tail = self.tail?.next
 83         self.tail?.prev = nil
 84         self.size -= 1
 85         if self.size == 0 {
 86             self.head = nil
 87             self.tail = nil
 88         }
 89         
 90         return true
 91 
 92     }
 93     
 94     /** Get the front item from the deque. */
 95     func getFront() -> Int {
 96         return self.head?.val ?? -1
 97     }
 98     
 99     /** Get the last item from the deque. */
100     func getRear() -> Int {
101         return self.tail?.val ?? -1
102     }
103     
104     /** Checks whether the circular deque is empty or not. */
105     func isEmpty() -> Bool {
106         return self.size == 0
107     }
108     
109     /** Checks whether the circular deque is full or not. */
110     func isFull() -> Bool {
111         return self.size == self.maxSize
112     }
113     
114     func getList() -> [Int] {
115         var l: [Int] = []
116 
117         var node = self.head
118         while node != nil {
119             l.append(node!.val)
120             node = node!.prev
121         }
122         
123         return l
124     }
125 }

 1 class MyCircularDeque {
 2     
 3     private var array = [Int]()
 4     private var maxSize = 0
 5     /** Initialize your data structure here. Set the size of the deque to be k. */
 6     init(_ k: Int) {
 7         maxSize = k
 8     }
 9     
10     /** Adds an item at the front of Deque. Return true if the operation is successful. */
11     func insertFront(_ value: Int) -> Bool {
12         guard array.count < maxSize else {
13             return false
14         }
15         
16         array.insert(value, at: 0)
17         return true
18     }
19     
20     /** Adds an item at the rear of Deque. Return true if the operation is successful. */
21     func insertLast(_ value: Int) -> Bool {
22         guard array.count < maxSize else {
23             return false
24         }
25         array.append(value)
26         return true
27     }
28     
29     /** Deletes an item from the front of Deque. Return true if the operation is successful. */
30     func deleteFront() -> Bool {
31         guard array.count >= 1 else {
32             return false
33         }
34         
35         array.remove(at: 0)
36         return true
37     }
38     
39     /** Deletes an item from the rear of Deque. Return true if the operation is successful. */
40     func deleteLast() -> Bool {
41         guard array.count >= 1 else {
42             return false
43         }
44         
45         array.removeLast()
46         return true 
47     }
48     
49     /** Get the front item from the deque. */
50     func getFront() -> Int {
51         guard let first = array.first else {
52             return -1
53         }
54         
55         return first
56     }
57     
58     /** Get the last item from the deque. */
59     func getRear() -> Int {
60         guard let last = array.last else {
61             return -1
62         }
63         
64         return last
65  
                       
                    
                    
 
                      




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