摘要：
27. Remove Element Given an array and a value, remove all instances of that value in place and return the new length. Do not allocate extra space for 阅读全文
摘要：
24. Swap Nodes in Pairs Given a linked list, swap every two adjacent nodes and return its head. For example,Given 1->2->3->4, you should return the li 阅读全文
摘要：
20. Valid Parentheses Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. The brack 阅读全文