codeforces 691F(组合数计算)
Couple Cover, a wildly popular luck-based game, is about to begin! Two players must work together to construct a rectangle. A bag with nballs, each with an integer written on it, is placed on the table. The first player reaches in and grabs a ball randomly (all balls have equal probability of being chosen) — the number written on this ball is the rectangle's width in meters. This ball is not returned to the bag, and the second player reaches into the bag and grabs another ball — the number written on this ball is the rectangle's height in meters. If the area of the rectangle is greater than or equal some threshold p square meters, the players win. Otherwise, they lose.
The organizers of the game are trying to select an appropriate value for p so that the probability of a couple winning is not too high and not too low, but they are slow at counting, so they have hired you to answer some questions for them. You are given a list of the numbers written on the balls, the organizers would like to know how many winning pairs of balls exist for different values of p. Note that two pairs are different if either the first or the second ball is different between the two in pair, and two different balls with the same number are considered different.
The input begins with a single positive integer n in its own line (1 ≤ n ≤ 106).
The second line contains n positive integers — the i-th number in this line is equal to ai (1 ≤ ai ≤ 3·106), the number written on the i-th ball.
The next line contains an integer m (1 ≤ m ≤ 106), the number of questions you are being asked.
Then, the following line contains m positive integers — the j-th number in this line is equal to the value of p (1 ≤ p ≤ 3·106) in the j-th question you are being asked.
For each question, print the number of winning pairs of balls that exist for the given value of p in the separate line.
5
4 2 6 1 3
4
1 3 5 8
20
18
14
10
2
5 6
2
30 31
2
0 思路:可以先预处理出乘积小于某个数的方案数。先用一个数组统计每个数字出现的次数,再枚举最大数以内的每个数,算出每个乘积,用乘法原理和加法原理做出可以得到该乘积的方案数,最后求出前缀为小于等于这个数的方案数。询问时只需总数减去小于这个数的方案数即可。
#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<queue>
using namespace std;
int n,a[],tot[];
long long f[];
int main()
{
scanf("%d",&n);
int i,j;
memset(tot,,sizeof(tot));
int mx=;
for (i=;i<=n;i++) scanf("%d",&a[i]),tot[a[i]]++,mx=max(mx,a[i]);
//cout<<mx<<endl;
for (i=;i<=mx;i++)
for (j=;j<=mx;j++)
{
if (1ll*i*j>) break;
if (i!=j) f[i*j]+=1ll*tot[i]*tot[j];
else f[i*j]+=max(1ll*tot[i]*(tot[i]-),0ll);
}
for (i=;i<=;i++) f[i]+=f[i-];
//cout<<"hhhhhhhh"<<endl;
int q;
scanf("%d",&q);
while (q--)
{
int x;
scanf("%d",&x);
printf("%lld\n",1ll*n*(n-)-f[x-]);
}
return ;
}
codeforces 691F(组合数计算)的更多相关文章
- C++单元测试 之 gtest -- 组合数计算.
本文将介绍如何使用gtest进行单元测试. gtest是google单元测试框架.使用非常方便. 首先,下载gtest (有些google项目包含gtest,如 protobuf),复制目录即可使用. ...
- 纪中集训2020.02.05【NOIP提高组】模拟B 组总结反思——【佛山市选2010】组合数计算,生成字符串 PPMM
目录 JZOJ2290. [佛山市选2010]组合数计算 比赛时 之后 JZOJ2291. [佛山市选2010]生成字符串 比赛时 之后 JZOJ2292. PPMM 比赛时 之后 JZOJ2290. ...
- [ An Ac a Day ^_^ ] CodeForces 691F Couple Cover 花式暴力
Couple Cover Time Limit: 3000MS Memory Limit: 524288KB 64bit IO Format: %I64d & %I64u Descri ...
- 组合数计算-java
排列组合是计算应用经常使用的算法,通常使用递归的方式计算,但是由于n!的过于大,暴力计算很不明智.一般使用以下两种方式计算. 一,递归的思想:假设m中取n个数计算排列组合数,表示为comb(m,n). ...
- Gym100947E || codeforces 559c 组合数取模
E - Qwerty78 Trip Time Limit:2000MS Memory Limit:65536KB 64bit IO Format:%I64d & %I64u S ...
- codeforces 691F 暴力
传送门:https://codeforces.com/contest/691/problem/F 题意:给你n个数和q次询问,每次询问问你有多少对ai,aj满足ai*aj>=q[i],注意 a* ...
- Educational Codeforces Round 14 - F (codeforces 691F)
题目链接:http://codeforces.com/problemset/problem/691/F 题目大意:给定n个数,再给m个询问,每个询问给一个p,求n个数中有多少对数的乘积≥p 数据范围: ...
- [leetcode] 题型整理之数字加减乘除乘方开根号组合数计算取余
需要注意overflow,特别是Integer.MIN_VALUE这个数字. 需要掌握二分法. 不用除法的除法,分而治之的乘方 2. Add Two Numbers You are given two ...
- codeforces 691F Couple Cover 暴力
分析:开一个300w的数组,统计,然后nlogn统计每个值在在序对第一个出现有多少种情况 时间复杂度:O(nlogn) n在3e6数量级 #include<cstdio> #include ...
随机推荐
- (六)SpringIoc之延时加载
Spring容器初始化时将所有scope = singleton的bean进行实例化. 通常情况下这是一件好事,因为这样在配置中的错误会更容易发现.但是如果不想spring容器初始化就实例化就要用到延 ...
- [BZOJ2005][NOI2010]能量采集 数学
题目链接:http://www.lydsy.com/JudgeOnline/problem.php?id=2005 发现与$(0,0)$连线斜率相同的点会被挡住.也就是对于$(a,b)$且$gcd(a ...
- GridView 中绑定DropDownList ,下拉框默认选中Label的值
在GridView中,我们 有时候要绑定值. 前台绑定的代码可以这样 <asp:TemplateField HeaderText="当前状态" ItemStyle-Horiz ...
- 请大家帮我找一找bug —— 一个MySQL解析程序(JAVA实现)
周末两天我写了一个MySQLParser.写这个东西的目的是:公司的一个项目中需要对数据打版本号(每个表的每条记录要有一个版本号字段,这个字段需要由框架自动打上去,而不是由程序员来做). 所以,我写的 ...
- Katalon Studio 安装 配置 简单使用
本教程只针对Katalon Studio进行演示操作. 一.下载 Katalon 官网下载地址:https://www.katalon.com/download/ (需要注册账号) 二.解压.配置 直 ...
- 从Code::Blocks到Dev–C++,Dev-C++安装调试一条龙
关于单文件调试 Codeblocks只支持单文件编译,不支持单文件调试,只有整个工程才能调试,还有路径名里不能有中文和空格,很坑的!就因为这个弃用了. 去你的吧! 老子用别的了 谁支持单文件编译和调试 ...
- CentOS7 Install Shipyard
# 采集木jj 原文:http://www.cnblogs.com/caoguo/p/5735189.html # CentOS7 Install Shipyard# yum install dock ...
- 【转】Google Chrome浏览器调试
作为Web开发人员,我为什么喜欢Google Chrome浏览器 [原文地址:http://www.cnblogs.com/QLeelulu/archive/2011/08/28/2156402.ht ...
- linux crontab创建计划任务
1.编辑计划任务 编辑crontab文件 crontab -e 2.查看计划任务日志 查看crontab日志 tail -100f /var/log/cron 3.创建计划任务格式 (1)基本格式 : ...
- CAD参数绘制实心圆弧填充(网页版)
js中实现代码说明: function DrawPathToHatch1() { //把路径的开始位置移动指定的点 //参数一为点的X坐标 ,参数二为点的Y坐标,参数三为该点处开始宽度,对Polyli ...