题目链接:http://codeforces.com/contest/340/problem/E E. Iahub and Permutations time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Iahub is so happy about inventing bubble sort graphs that he's sta…

D. Iahub and Xors   Iahub does not like background stories, so he'll tell you exactly what this problem asks you for. You are given a matrix a with n rows and n columns. Initially, all values of the matrix are zeros. Both rows and columns are 1-based…

Codeforces Round #198 (Div. 2) 昨天看到奋斗群的群赛,好奇的去做了一下, 大概花了3个小时Ak,我大概可以退役了吧 那下面来稍微总结一下 A. The Wall Iahub and his friend Floyd have started painting a wall. Iahub is painting the wall red and Floyd is painting it pink. You can consider the wall being mad…

Codeforces Round #485 (Div. 2) E. Petr and Permutations 题目连接: http://codeforces.com/contest/987/problem/E Description Petr likes to come up with problems about randomly generated data. This time problem is about random permutation. He decided to gene…

A.The Wall 题意:两个人粉刷墙壁,甲从粉刷标号为x,2x,3x...的小块乙粉刷标号为y,2y,3y...的小块问在某个区间内被重复粉刷的小块的个数. 分析:求出x和y的最小公倍数,然后做一个一维的区间减法就可以了. #include <cstdlib> #include <cstdio> #include <cstring> #include <algorithm> using namespace std; typedef long long L…

E. Iahub and Permutations Iahub is so happy about inventing bubble sort graphs that he's staying all day long at the office and writing permutations. Iahubina is angry that she is no more important for Iahub. When Iahub goes away, Iahubina comes to h…

A. The Wall 求下gcd即可. B. Maximal Area Quadrilateral 枚举对角线,根据叉积判断顺.逆时针方向构成的最大面积. 由于点坐标绝对值不超过1000,用int比较快. C. Tourist Problem 假设序列为\(p_1,p_2,...,p_n\),则距离总和为\(,,,p_1,|p_2-p_1|,...,|p_n-p_{n-1}|\). 第1个点\(p_1\)的贡献为\(\sum a_i(n-1)!\) \(|p_i-p_{i-1}|\)的贡献为\…

D. Bubble Sort Graph time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Iahub recently has learned Bubble Sort, an algorithm that is used to sort a permutation with n elements a1, a2, ..., an …

http://codeforces.com/contest/341 赛后做的虚拟比赛,40分钟出了3题,RP爆发. A计数问题 我们可以对每对分析,分别对每对<a, b>(a走到b)进行统计,那么这对<a, b>产生的期望为distance(a, b)/n (把这一对选出来以后相当于一个点,那么分子distance(a, b)*(n-1)!,分母n!,     (n-1)被约掉了.) 这样的算法是O(n^2)的,问题转化为统计所有对<a, b> 的距离.我们可以对输入的…

C. Tourist Problem time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Iahub is a big fan of tourists. He wants to become a tourist himself, so he planned a trip. There are n destinations on a…