摘要： Remove Nth Node From End of ListGiven a linked list, remove thenthnode from the end of list and return its head.For example,Given linked list: 1->2->3->4->5, and n = 2.After removing the second node from the end, the linked list becomes 1->2->3->5.Note:Givennwill always be valid 阅读全文

摘要： Letter Combinations of a Phone Number2013.12.6 19:52Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone buttons) is given below.Input:Digit string "23"Output: ["ad", "ae" 阅读全文