[LeetCode] Implement Queue using Stacks
来源:互联网 发布:des算法优缺点 编辑:程序博客网 时间:2024/05/01 13:42
Implement Queue using Stacks
Implement the following operations of a queue using stacks.
- push(x) -- Push element x to the back of queue.
- pop() -- Removes the element from in front of queue.
- peek() -- Get the front element.
- empty() -- Return whether the queue is empty.
Notes:
- You must use only standard operations of a stack -- which means only
push to top
,peek/pop from top
,size
, andis empty
operations are valid. - Depending on your language, stack may not be supported natively. You may simulate a stack by using a list or deque (double-ended queue), as long as you use only standard operations of a stack.
- You may assume that all operations are valid (for example, no pop or peek operations will be called on an empty queue).
解题思路:
用两个栈来模拟队列。其中一个栈做缓存之用,另外一个栈只接受。push操作,直接放入接收之栈中。pop操作,若缓存栈存在数据,则从缓存栈中弹出。若缓存栈为空,则将接收栈的数据弹出并插入到缓存栈中,再从缓存栈中弹出。peek操作与pop操作类似。当且仅当两个栈都为空时,empty才返回true。
class Queue {public: // Push element x to the back of queue. void push(int x) { stacks[0].push(x); } // Removes the element from in front of queue. void pop(void) { if(stacks[1].empty()){ while(!stacks[0].empty()){ stacks[1].push(stacks[0].top()); stacks[0].pop(); } } stacks[1].pop(); } // Get the front element. int peek(void) { if(stacks[1].empty()){ while(!stacks[0].empty()){ stacks[1].push(stacks[0].top()); stacks[0].pop(); } } return stacks[1].top(); } // Return whether the queue is empty. bool empty(void) { return stacks[0].empty() && stacks[1].empty(); } private: stack<int> stacks[2];};
0 0
- leetcode :Implement Queue using Stacks
- [LeetCode] Implement Queue using Stacks
- LeetCode Implement Queue using Stacks
- LeetCode || Implement Queue using Stacks
- leetcode Implement Queue using Stacks
- Leetcode Implement Queue using Stacks
- [LeetCode]Implement Queue using Stacks
- 【Leetcode】Implement Queue using Stacks
- LeetCode Implement Queue using Stacks
- Leetcode: Implement Queue using Stacks
- [leetcode] Implement Queue using Stacks
- 【leetcode】Implement Queue using Stacks
- [Leetcode]Implement Queue using Stacks
- [leetcode] Implement Queue using Stacks
- LeetCode-Implement Queue using Stacks
- LeetCode Implement Queue using Stacks
- Leetcode: Implement Queue using Stacks
- LeetCode:Implement Queue using Stacks
- 浙江工业大学简易绩点计算器c++版
- MAC环境下生成Apple证书教程
- 图的宽度优先遍历--最少转机
- 台大机器学习基石笔记(四)——VC 维3
- 【学习笔记】Web Application Artchitectures (1)
- [LeetCode] Implement Queue using Stacks
- 【机器学习系列】机器学习界大牛林达华推荐的书籍
- VVDocumenter(Xcode标准注释符)的安装问题解决方案
- 判断我国公民的身份证是否合法
- LeetCode-Pow(x, n)-解题报告
- LeetCode Number of 1 Bits
- 包含min函数的栈
- 进制转换(数据存储)
- 《opencv入门》