1.题目 2.思路 3.java代码 import java.util.LinkedList; import java.util.Queue; public class MyStack { private Queue<Integer> q1=new LinkedList<Integer>(); private Queue<Integer> q2=new LinkedList<Integer>(); /** Push element x onto stack.…

class Stack { public: // Push element x onto stack. void push(int x) { int len = nums.size(); nums.push(x); ; i < len; ++i) { nums.push(nums.front()); nums.pop(); } } // Removes the element on top of the stack. void pop() { nums.pop(); } // Get the t…

[20]Valid Parentheses (2018年11月28日,复习, ko) 给了一个字符串判断是不是合法的括号配对. 题解:直接stack class Solution { public: bool isValid(string s) { set<char> st{'(', '[', '{'}; map<char, char> mp{{'(', ')'}, {'{', '}'}, {'[', ']'}}; stack<char> stk; for (auto…

232 - 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 whe…

一.Implement Stack using Queues 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 em…

232. Implement Queue using Stacks Total Accepted: 27024 Total Submissions: 79793 Difficulty: Easy 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 o…

155. Min Stack class MinStack { public: /** initialize your data structure here. */ MinStack() { } void push(int x) { if(s1.empty() && s2.empty()){ s1.push(x); s2.push(x); } else{ if(x < s2.top()){ s1.push(x); s2.push(x); } else{ s1.push(x); s2…

Implement Queue by Two 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…

题目: 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 on…

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