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…

[传送门] FFT第四题! 暑假的时候只会点分,然后合并是暴力合并的...水过去了... 其实两条路径长度的合并就是卷积的过程嘛,每次统计完路径就自卷积一下. 刚开始卷积固定了值域.T了.然后就不偷懒了,每次取最大权值乘二去找值域了. #include <bits/stdc++.h> const double pi = acos(-1.0); struct Complex { double r, i; void clear() { r = i = 0.0; } Complex(, ): r(r…

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…

vjudge 给定一棵边长都是\(1\)的树,求有多少条路径长度为质数 树上路径自然是点分治去搞,但是发现要求是长度为质数,总不能对每一个质数都判断一遍吧 自然是不行的,这个东西显然是一个卷积,我们合并的时候显然可以直接大力\(NTT\) 但是需要注意的是我们访问子树的顺序必须是先访问深度小的子树,否则轻松被菊花加长链卡掉 但是\(CodeChef\)数据水啊,就这样直接搞过去了 代码 #include<algorithm> #include<iostream> #include&…

Prime Distance Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 12512   Accepted: 3340 Description The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number th…

题目链接: http://codeforces.com/contest/161/problem/D D. Distance in Tree time limit per test 3 secondsmemory limit per test 512 megabytes 问题描述 A tree is a connected graph that doesn't contain any cycles. The distance between two vertices of a tree is th…

树链剖分+可持久化线段树....这个一眼可以看出来, 因为可持久化所以写了标记永久化(否则就是区间修改的线段树的持久化..不会), 结果就写挂了, T得飞起...和管理员拿数据调后才发现= = 做法:码码码码码码码码...码完就AC啦. O(M log N) ------------------------------------------------------------------- #include<cstdio> #include<cctype> #include<…

10140 - Prime Distance 题目链接 题意:求[l,r]区间内近期和最远的素数对. 思路:素数打表,打到sqrt(Max)就可以,然后利用大的表去筛素数.因为[l, r]最多100W.所以能够去遍历一遍.找出答案. 注意1的情况,一開始没推断1,结果WA了 代码: #include <stdio.h> #include <string.h> #include <algorithm> using namespace std; #define INF 0x…

题目链接:poj 2689 Prime Distance 题意: 给你一个很大的区间(区间差不超过100w),让你找出这个区间的相邻最大和最小的两对素数 题解: 正向去找这个区间的素数会超时,我们考虑逆向思维: 我们先用线性筛 筛出前50000的素数,在int范围内的区间的合数的因子都在我们之前筛出来了, 然后我们就把这个区间的合数标记出来,剩下的就是素数了. 标记合数也是用全部的素数去筛一下,这样就能快速的标记这个区间的合数,然后在暴力枚举一下这个区间,更新一下答案. #include<cst…

/* * 二次筛素数 * POJ268----Prime Distance(数论,素数筛) */ #include<cstdio> #include<vector> using namespace std; const int maxn = 1000005; typedef long long LL; bool is_prime_small[maxn]; bool is_prime[maxn]; vector <int> res; int main() { LL l,u…

1619: [例 1]Prime Distance 题目描述 原题来自:Waterloo local,题面详见 POJ 2689 给定两个整数 L,R,求闭区间 [L,R] 中相邻两个质数差值最小的数对与差值最大的数对.当存在多个时,输出靠前的素数对. 输入格式 多组数据.每行两个数 L,R. 输出格式 详见输出样例. 样例 样例输入 2 17 14 17 样例输出 2,3 are closest, 7,11 are most distant. There are no adjacent pri…

题目链接:传送门 题目: Prime Distance Time Limit: 1000MS Memory Limit: 65536K Total Submissions: Accepted: Description The branch of mathematics called number theory and itself). The first prime numbers are ,,, but they quickly become less frequent. One of the…

Prime Distance Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 13961   Accepted: 3725 Description The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number th…

UVA10140 Prime Distance 给定两个整数L,R(1<=L<=R<=2^{31},R-L<=10^6)L,R(1<=L<=R<=231,R−L<=106),求闭区间 [L,R][L,R] 中相邻两个质数的差的最小值和最大值是多少,分别输出这两个质数. 首先我们发现:R-LR−L 的范围很小,我们应该要能够快速求出 L\sim RL∼R 之间的质数. 显然有推论:任意一个合数 xx 必定包含一个不超过 \sqrt xx​ 的质因子. 所以我们…

CF161D Distance in Tree LG传送门 长链剖分板子题. 长链剖分那么好写,跑得又快,为什么要写点分治呢?完了我现在看一道点分治题就想写长链剖分 如果还不会长链剖分请看我博客. 没什么好说的,时空复杂度\(O(n)\)直接洛谷rank1. #include<cstdio> #include<cctype> #define R register #define I inline using namespace std; const int S=50003,N=10…

Prime Distance Time Limit: 2 Seconds      Memory Limit: 65536 KB The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number theoreticians for thousands of years is the ques…

2017-10-03 11:29:20 writer:pprp 来源:kuangbin模板 从已经筛选好的素数中筛选出规定区间的素数 /* *prime DIstance *给出一个区间[L,U],找到相邻的距离最近的两个素数的和 *还有距离最远的两个素数 *1 <= L < U <= 2147483647 *区间长度不超过1000000 *就是要筛选出[L,U]之间的素数 */ #include <iostream> #include <cstdio> #inc…

[CF161.D] Distance in Tree time limit per test 3 seconds memory limit per test 512 megabytes A tree is a connected graph that doesn't contain any cycles. The distance between two vertices of a tree is the length (in edges) of the shortest path betwee…

题目链接 Distance in Tree $k <= 500$ 这个条件十分重要. 设$f[i][j]$为以$i$为子树,所有后代中相对深度为$j$的结点个数. 状态转移的时候,一个结点的信息由他的儿子转移过来. 那么一边进行状态转移,一边统计答案即可. #include <bits/stdc++.h> using namespace std; ][], deep[]; vector <]; int n, k, x, y; long long ans; void dfs(int…

[题解]UVA10140 Prime Distance 哈哈哈哈\(miller-rabbin\)水过去了哈哈哈 还能怎么办呢?\(miller-rabbin\)直接搞.枚举即可,还跑得飞快. 当然此题由于\(20000^2 >2^{31}\),直接预处理\(20000\)内的质数就好了 放mr的代码 #include<bits/stdc++.h> using namespace std;typedef long long ll; #define DRP(t,a,b) for(regis…

Distance in Tree CodeForces - 161D 题意:给一棵n个结点的树,任意两点之间的距离为1,现在有点u.v,且u与v的最短距离为k,求这样的点对(u,v)的个数((u,v)/(v,u)算一对). 方法: ans[i][k]表示与i结点距离为k的子结点个数 ans[i][k]=sum{ans[son][k-1]} ans[i][0]=1 sum[i]表示(u,v)都为i的子结点且(u,v)的最短路径过i点 sum[i]=sum{ans[i][p]*ans[i][k-p]…

                                                Prime Distance 只会埃氏筛法的弱鸡今天读了读挑战程序设计120页,明白了求小区间内素数的方法. 突然发现挑战真的是本很好的书,很具有引导性,不过很多地方没有详细证明介绍,适用进阶选手. 题意:给你两个数,求[a,b]内相邻最近的素数对与相邻最远的素数对.但是,a,b的很大,同时b-a<=1e6. 思路:判断一个数b是否为素数只需判断i*i<=b即可,也就是说小于等于b的合数的最大素因子…

Prime Distance Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 12811   Accepted: 3420 Description The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number th…

Prime Distance Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 9944   Accepted: 2677 Description The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number the…

2689 -- Prime Distance 没怎么研究过数论,还是今天才知道有素数二次筛法这样的东西. 题意是,要求求出给定区间内相邻两个素数的最大和最小差. 二次筛法的意思其实就是先将1~sqrt(b)内的素数先筛出来,然后再对[a,b]区间用那些筛出来的素数再次线性筛. 代码如下: #include <cstdio> #include <cstring> #include <algorithm> #include <iostream> using na…

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…

The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number theoreticians for thousands of years is the question of primality. A prime number is a number that is has no prop…

题目链接:http://poj.org/problem?id=2689 Time Limit: 1000MS Memory Limit: 65536K Description The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number theoreticians for thousan…

A tree is a connected graph that doesn't contain any cycles. The distance between two vertices of a tree is the length (in edges) of the shortest path between these vertices. You are given a tree with n vertices and a positive number k. Find the numb…

The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number theoreticians for thousands of years is the question of primality. A prime number is a number that is has no prop…