摘要：
Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n.For example:Given n = 13,Return 6... 阅读全文
摘要：
Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.Supposed the linked list is1 -> 2 -> 3 -> ... 阅读全文