标签:init bool boolean logs div nbsp ret standard move
Implement the following operations of a queue using stacks.
Notes:
push to top
, peek/pop from top
, size
, and is empty
operations are valid.题目含义:使用stack来实现queue的功能
1 class MyQueue { 2 Stack<Integer> input = new Stack(); 3 Stack<Integer> output = new Stack(); 4 /** Initialize your data structure here. */ 5 public MyQueue() { 6 7 } 8 9 /** Push element x to the back of queue. */ 10 public void push(int x) { 11 input.push(x); 12 } 13 14 /** Removes the element from in front of queue and returns that element. */ 15 public int pop() { 16 peek(); 17 return output.pop(); 18 } 19 20 /** Get the front element. */ 21 public int peek() { 22 if (output.empty()) 23 while (!input.empty()) 24 output.push(input.pop()); 25 return output.peek(); 26 27 } 28 29 /** Returns whether the queue is empty. */ 30 public boolean empty() { 31 return input.empty() && output.empty(); 32 } 33 }
232. Implement Queue using Stacks
标签:init bool boolean logs div nbsp ret standard move
原文地址:http://www.cnblogs.com/wzj4858/p/7725664.html