1 class MyStack
2 {
3 private Queue q1;
4 private Queue q2;
5
6 public MyStack(int size)
7 {
8 this.q1 = new Queue(size);
9 this.q2 = new Queue(size);
10 }
11
12 public boolean isFull()
13 {
14 return q1.isFull();
15 }
16
17 public boolean isEmpty()
18 {
19 return q1.isEmpty();
20 }
21
22 //时间复杂度: O(n)
23 public void push(int k) throws Exception
24 {
25 if(this.isFull())
26 throw new Exception("Overflow.");
27 else
28 {
29 while(!this.q1.isEmpty())
30 this.q2.EnQueue(this.q1.DeQueue());
31 this.q1.EnQueue(k);
32 while(!this.q2.isEmpty())
33 this.q1.EnQueue(this.q2.DeQueue());
34 }
35 }
36
37 //时间复杂度: O(1)
38 public int pop() throws Exception
39 {
40 if(this.isEmpty())
41 throw new Exception("Underflow");
42 else
43 return this.q1.DeQueue();
44 }
45 }
46
47 class Queue
48 {
49 private int front;
50 private int rear;
51 private int[] a;
52
53 public Queue(int size)
54 {
55 this.front = this.rear = 0;
56 this.a = new int[size];
57 }
58
59 public boolean isFull()
60 {
61 return (this.rear + 1) % this.a.length == this.front;
62 }
63
64 public boolean isEmpty()
65 {
66 return this.rear == this.front;
67 }
68
69 public void EnQueue(int k) throws Exception
70 {
71 //该判断是冗余的
72 /*if(this.isFull())
73 *
74 throw new Exception("Overflow.");*/
75 //else
76 {
77 this.a[this.rear] = k;
78 this.rear = (this.rear + 1) % this.a.length;
79 }
80
81 }
82
83 public int DeQueue() throws Exception
84 {
85 //该判断是冗余的
86 /*if(this.isEmpty())
87 throw new Exception("Underflow.");*/
88 //else
89 {
90 int key = this.a[front];
91 this.front = (this.front + 1) % this.a.length;
92 return key;
93 }
94 }
95
96 public int getLength()
97 {
98 return (this.rear - this.front + this.a.length) % this.a.length;
99 }
100 }
