Question: 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.…

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…

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…

Description: 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 empt…

题意: 用栈来实现队列. 思路: 一个栈是不够的,至少要两个. (1)插入.永远只插入到stack1中(插到栈顶). (2)弹出.如果stack2不为空,直接弹出stack2的栈顶,否则,将stack1中的所有元素转移到stack2中,栈顶自然就是队头了,再弹出. (3)返回队头.与(2)一样. (4)是否为空.判断两个栈是否同时为空即可. 只要保证stack2为空时才可以将stack1转移到stack2中,就可以保证两边并不会产生混乱而出错. class Queue { /* // Push…

Implement the following operations of a stack using queues. push(x) -- Push element x onto stack. pop() -- Removes the element on top of the stack. top() -- Get the top element. empty() -- Return whether the stack is empty. Notes: You may assume that…

Implement a trie with insert, search, and startsWith methods. Note:You may assume that all inputs are consist of lowercase letters a-z. 这道题让我们实现一个重要但又有些复杂的数据结构-字典树, 又称前缀树或单词查找树,详细介绍可以参见网友董的博客,例如,一个保存了8个键的trie结构,"A", "to", "tea&quo…

Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. Update (2014-11-02): The signature of the function had been updated to return the index instead of the pointer. If you still…

Implement the following operations of a stack using queues. push(x) -- Push element x onto stack. pop() -- Removes the element on top of the stack. top() -- Get the top element. empty() -- Return whether the stack is empty. Notes: You must use only s…

Github leetcode 我的解题仓库   https://github.com/interviewcoder/leetcode 题目: Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. Update (2014-11-02):The signature of the function ha…