摘要： 转载关于线段树的讲解好久没写过算法了，添一个吧，写一个线段树的入门知识，比较大众化。上次在湖大，其中的一道题数据很强，我试了好多种优化都TLE，相信只能用线段树才能过。回来之后暗暗又学了一次线段树，想想好像是第三次学了，像网络流一样每学一次都有新的体会。把问题简化一下：在自然数，且所有的数不大于30000的范围内讨论一个问题：现在已知n条线段，把端点依次输入告诉你，然后有m个询问，每个询问输入一个点，要求这个点在多少条线段上出现过；最基本的解法当然就是读一个点，就把所有线段比一下，看看在不在线段中；每次询问都要把n条线段查一次，那么m次询问，就要运算m*n次，复杂度就是O(m*n)这道题m和n 阅读全文

摘要： You have a necklace of N red, white, or blue beads (3<=N<=350) some of which are red, others blue, and others white, arranged at random. Here are two examples for n=29: 1 2 1 2 r b b r b r r b r b ... 阅读全文

摘要： Is Friday the 13th really an unusual event?That is, does the 13th of the month land on a Friday less often than on any other day of the week? To answer this question, write a program that will compute the frequency that the 13th of each month lands on Sunday, Monday, Tuesday, Wednesday, Thursday, Fr 阅读全文

摘要： A group of NP (2 ≤ NP ≤ 10) uniquely named friends has decided to exchange gifts of money. Each of these friends might or might not give some money to any or all of the other friends. Likewise, each friend might or might not receive money from any or all of the other friends. Your goal in this probl 阅读全文

摘要： It is a well-known fact that behind every good comet is a UFO. These UFOs often come to collect loyal supporters from here on Earth. Unfortunately, they only have room to pick up one group of followers on each trip. They do, however, let the groups know ahead of time which will be picked up for each 阅读全文