摘要：
感觉就是求1~ n 然后家在中间的k位置，求1~ k-1 的和等于k+1~n题目：Street NumbersA computer programmer lives in a street with houses numbered consecutively (from 1) down one side of the street. Every evening she walks her dog by leaving her house and randomly turning left or right and walking to the end of the street and bac 阅读全文
