link on JianShu 栈stack valid parentheses Given a string containing just the characters ‘(’, ‘)’, ‘{’, ‘}’, ‘[’ and ‘]’, determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Note that an empty string is also considered valid. 先从最
link on JianShu 栈stack 496. Next Greater Element I Easy You are given two arrays (without duplicates) nums1 and nums2 where nums1’s elements are subset of nums2. Find all the next greater numbers for nums1's elements in the corresponding places of nums2. The Next Greater Number of a number x in nums1 is the first greater number to its
link on JianShu 栈stack 42. Trapping Rain Water Hard Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining. The above elevation map is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of rain water (blue section) are being trapped. Thanks Marcos for contributing this image! Example:
link on JianShu 栈stack 71. simplify path Medium Given an absolute path for a file (Unix-style), simplify it. Or in other words, convert it to the canonical path. In a UNIX-style file system, a period . refers to the current directory. Furthermore, a double period .. moves the directory up a level. For more information, see: Absolute path vs relative path in Linux/Unix Note that
link on JianShu 栈stack 225. Implement Stack using Queues Easy 232. Implement Queue using Stacks Easy 这两道提互为实现，刚好放到一起学习。既然两种数据结构可以互相实现，可以看看有什么相似之处。 队列qu
