摘要：
Implement a basic calculator to evaluate a simple expression string. The expression string contains only non-negative integers, +, -, *, / operators a 阅读全文
摘要：
Given a string s, you are allowed to convert it to a palindrome by adding characters in front of it. Find and return the shortest palindrome you can f 阅读全文
摘要：
The key of Kmp is to build a look up table that records the match result of prefix and postfix. Value in the table means the max len of matching subst 阅读全文
摘要：
Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. Note: For the purpose of this problem, w 阅读全文