摘要:
Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 题意: 判断一个链表是否有环。 解决方案: 双指针,快指针每次走两步,慢指针每次 阅读全文
摘要:
Given a positive integer num, write a function which returns True if num is a perfect square else False. Note: Do not use any built-in library functio 阅读全文
摘要:
Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, /. Each operand may be an integer or another e 阅读全文