James Pan

原题网址：https://leetcode.com/problems/implement-stack-using-queues/ Implement the following operations of a stack using queues. push(x) -- Push element x onto stack.pop() -- Removes the element o

原题网址：https://leetcode.com/problems/implement-queue-using-stacks/ mplement the following operations of a queue using stacks. push(x) -- Push element x to the back of queue.pop() -- Removes the

原题网址：https://leetcode.com/problems/basic-calculator/ Implement a basic calculator to evaluate a simple expression string. The expression string may contain open ( and closing parentheses ),

原题网址：https://leetcode.com/problems/sliding-window-maximum/ Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only

原题网址：https://leetcode.com/problems/design-hit-counter/ Design a hit counter which counts the number of hits received in the past 5 minutes. Each function accepts a timestamp parameter (in seco