Selecting courses Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 62768/32768 K (Java/Others) Total Submission(s): 1856    Accepted Submission(s): 469 Problem Description     A new Semester is coming and students are troubling for selecting c…

题意:给定一个图,问你只能向上向下,或者平着走,有多少种方法可以走到最后一个格. 析:首先先考虑,如果没有平的情况就是calelan数了,现在有平的情况,那么就枚举呗,因为数很大,所以要用高精度. 答案应该是sum(C(n, 2*i)*C(n, i)/(i+1)) = a1 + a2 + a3 + ....,然后可以再化简一下,成为一个递推式ai = ai-1 * (n-2*i+1)*(n-2*i+2)/(k*(k+1)): 这次用记事本写的,然后没有测试,直接交的,虽然CE了一发,但还是挺好的…

hdu 4825 Xor Sum(trie+贪心) 刚刚补了前天的CF的D题再做这题感觉轻松了许多.简直一个模子啊...跑树上异或x最大值.贪心地让某位的值与x对应位的值不同即可. #include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <cmath> #define CLR(a,b) memset((a),(b),sizeof(…

option=com_onlinejudge&Itemid=8&category=471&page=show_problem&problem=4224" style="">题目链接:uva 1478 - Delta Wave 题目大意:对于每一个位置来说,能够向上,水平,向下.坐标不能位负.每次上下移动最多为1. 给定n问说有多少种不同的图.结果对10100取模. 解题思路:由于最后都要落回y=0的位置,所以上升的次数和下降的次数是同样的…

题目链接:https://vjudge.net/problem/HDU-3723 Delta Wave Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1468    Accepted Submission(s): 483 Problem Description A delta wave is a high amplitude brain…

Delta-wave HDU - 1030 A triangle field is numbered with successive integers in the way shown on the picture below. The traveller needs to go from the cell with number M to the cell with number N. The traveller is able to enter the cell through cell e…

[题目描述] Elections are coming. You know the number of voters and the number of parties — n and m respectively. For each voter you know the party he is going to vote for. However, he can easily change his vote given a certain amount of money. In particu…

Avin is studying series. A series is called "wave" if the following conditions are satisfied: 1) It contains at least two elements; 2) All elements at odd positions are the same; 3) All elements at even positions are the same; 4) Elements at odd…

Description     A new Semester is coming and students are troubling for selecting courses. Students select their course on the web course system. There are n courses, the ith course is available during the time interval (Ai,Bi). That means, if you wa…

problem description http://acm.hdu.edu.cn/showproblem.php?pid=1030 #include <cstdio> #include <cmath> #include <algorithm> int calPathLength(int x, int y) { //path length from 1 (1st line, lower) to a number in ith line is only differ by…