题意: 有一个\(N \times N\)的方阵,第\(x\)行第\(y\)列有\(C_{x,y}\)个点\((0 \leq C_{x,y} \leq 9)\). 任选两个不同的点,求两点欧几里德距离的均值(或期望). 然后按距离从小到大输出该距离的平方\(d_i\)和对应的点对数目\(c_i\). 分析: 首先要化二维为一维,一般来讲给点\((x,y)\)编号\(x \times N+y(0\leq x, y < N)\). 这里为了区分行和列从而方便计算距离,按照\(x \times 2N…

表示敲完多项式乘法&高精度乘法两道FFT模板题后就开始来磕这题了 这题相对而言应该不算模板题 不过神犇们肯定还是一眼看穿 如果原OJ访问速度较慢的话可以考虑戳这里 http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=153505 -----------------------------------------------------------------------------------------------------…

Prime Distance On Tree Problem description. You are given a tree. If we select 2 distinct nodes uniformly at random, what's the probability that the distance between these 2 nodes is a prime number? Input The first line contains a number N: the numbe…

题目链接:http://www.codechef.com/problems/PRIMEDST/ 题意:给出一棵树,边长度都是1.每次任意取出两个点(u,v),他们之间的长度为素数的概率为多大? 树分治,对于每个根出发记录边的长度出现几次,然后每次求卷积,用素数表查一下即可添加答案. #include<algorithm> #include<cstdio> #include<cmath> #include<cstring> #include<iostre…

最裸的点分治+fft,调了好久,太菜了.... #include<iostream> #include<cstring> #include<cstdio> #include<cmath> #include<algorithm> using namespace std; typedef long long ll; ,inf=1e9; ); int f[maxn],t,last[maxn],pre[maxn],other[maxn],siz[maxn…

题目 首先还没有安排座位的\(m-k\)个人之间是有顺序的,所以先把答案乘上\((m-k)!\),就可以把这些人看作不可区分的. 已经确定的k个人把所有座位分成了k+1段.对于第i段,如果我们能求出这一段恰好额外坐j人时的代价总和\(f_{i,j}\),并令\(f_{i,j}\)的普通生成函数为\(F_i(x)\),答案就是\(\prod F_i(x)\)的\(m-k\)次项系数. 先考虑k+1段中两边都有已经确定的人的k-1段.对于每一段i,枚举其中额外坐的人数j,现在考虑求出\(f_{i,j…

题目 Source https://icpcarchive.ecs.baylor.edu/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=4898 Description Do you like golf? I hate it. I hate golf so much that I decided to build the ultimate golf robot, a robot that wi…

题目 Source http://codeforces.com/problemset/problem/528/D Description Leonid works for a small and promising start-up that works on decoding the human genome. His duties include solving complex problems of finding certain patterns in long strings cons…

题目 Source http://acm.hust.edu.cn/vjudge/problem/19225 Description The Hamming distance between two strings of the same length is defined as the number of positions at which the corresponding characters are different. For example, the Hamming distance…

XM Reserves Time Limit: 10000/10000 MS (Java/Others)    Memory Limit: 102400/102400 K (Java/Others)Total Submission(s): 99    Accepted Submission(s): 45 Problem Description As an eligible Ingress Resistance Agent you should know your power source, th…