stack - The Poor Coder | Algorithm Solutions (Page 2)

leetcode

Leetcode - Implement Stack using Queues Solution

Implement a last in first out (LIFO) stack using only two queues. The implemented stack should support all the functions of a normal queue (push, top, pop, and empty). Implement the MyStack class: * void push(int x) Pushes element x to the top of the stack. * int pop() Removes the

leetcode

Leetcode - Min Stack Solution

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. Implement the MinStack class: * MinStack() initializes the stack object. * void push(val) pushes the element val onto the stack. * void pop() removes the element on the top of the stack. * int top() gets the

leetcode

Leetcode - Valid Parentheses Solution

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: 1. Open brackets must be closed by the same type of brackets. 2. Open brackets must