摘要： 1.问题规划 图1.推荐系统在研究什么？ 例子：预测电影的评分。 当知道n_u用户数,n_m电影数；r(i,j)用户j评价了电影i，那么就是1；y(i,j)如果r(i,j)为1，那么就给出评分。 问题就是根据现有数据训练学习算法，预测未评分的电影。 2.基于内容的推荐算法 图2.基于内容的推荐系统 阅读全文

摘要： Given a constant K and a singly linked list L, you are supposed to reverse the links of every K elements on L. For example, given L being 1→2→3→4→5→6, 阅读全文

摘要： To store English words, one method is to use linked lists and store a word letter by letter. To save some space, we may let the words share the same s 阅读全文

摘要： 1068 Find More Coins (30)（30 分） Eva loves to collect coins from all over the universe, including some other planets like Mars. One day she visited a u 阅读全文

摘要： The task is simple: given any positive integer N, you are supposed to count the total number of 1's in the decimal form of the integers from 1 to N. F 阅读全文

摘要： Eva is trying to make her own color stripe out of a given one. She would like to keep only her favorite colors in her favorite order by cutting off th 阅读全文

摘要： 1.双链表中至多只有一个结点的后继指针为空（是）。 非循环双链表最后一个结点的后继指针为空； 循环双链表没有一个结点的后继指针为空； 综上，至多只有一个。（链表结构，也就是前驱节点，后继指针，以及本节点存储信息。） 2.在用邻接表表示图时，拓扑排序算法时间复杂度为( O(n+e))。//不是O(n* 阅读全文

摘要： 1040 Longest Symmetric String (25)（25 分） Given a string, you are supposed to output the length of the longest symmetric sub-string. For example, given 阅读全文

摘要： A gas station has to be built at such a location that the minimum distance between the station and any of the residential housing is as far away as po 阅读全文

摘要： 1.问题动机 图1.飞机发动机检测例子 对飞机引擎的例子，如果选取了两个特征x1热量产生度，x2震动强度。并得到如下的图，如果有一个新的引擎来检测其是否正常，x_test，那么此时如果点落在和其他点正常内，那么就显示是正常，不需要进一步的检测，但是如果在右下角绿色的，那么就是异常的，需要进一步地检测 阅读全文