codeforces 691F F. Couple Cover(组合计数)
题目链接:
3 seconds
512 megabytes
standard input
standard output
Couple Cover, a wildly popular luck-based game, is about to begin! Two players must work together to construct a rectangle. A bag withn balls, 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 ≤ 10^6).
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 ≤ 3·10^6) 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 题意: 给一个数列,问这里面有多少对的积大于等于p; 思路:
由于询问太多,所以要降低复杂度,可以反方向考虑,可以用总的方案数减去小于p的方案数,小于p的方案数;
可以先把相同的数压缩,最的的复杂度是O(nlogn+m)
AC代码:
#include <bits/stdc++.h>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath> using namespace std; #define For(i,j,n) for(int i=j;i<=n;i++)
#define mst(ss,b) memset(ss,b,sizeof(ss)); typedef long long LL; template<class T> void read(T&num) {
char CH; bool F=false;
for(CH=getchar();CH<'0'||CH>'9';F= CH=='-',CH=getchar());
for(num=0;CH>='0'&&CH<='9';num=num*10+CH-'0',CH=getchar());
F && (num=-num);
}
int stk[70], tp;
template<class T> inline void print(T p) {
if(!p) { puts("0"); return; }
while(p) stk[++ tp] = p%10, p/=10;
while(tp) putchar(stk[tp--] + '0');
putchar('\n');
} const LL mod=1e9+7;
const double PI=acos(-1.0);
const LL inf=1e18;
const int N=3e6+10;
const int maxn=3e6;
const double eps=1e-10; int m,a[N],b[N];
LL num[N],sum[N],n;
void Init()
{
sort(a+1,a+n+1);
int cnt=0;
For(i,1,n)
{
if(a[i]==a[i-1])num[cnt]++;
else
{
++cnt;
b[cnt]=a[i];
num[cnt]=1;
}
}
For(i,1,cnt)
{
For(j,1,i)
{
if((LL)b[i]*b[j]>=maxn)break;
if(i==j)sum[b[i]*b[j]]+=num[i]*(num[i]-1);
else sum[b[i]*b[j]]+=2*num[i]*num[j];
}
}
//for(int i=1;i<30;i++)print(sum[i]);
For(i,1,maxn)sum[i]+=sum[i-1];
}
int main()
{
read(n);
For(i,1,n)read(a[i]);
Init();
read(m);
int p;
For(i,1,m)
{
read(p);
print((LL)n*(n-1)-sum[p-1]);
}
return 0;
}
codeforces 691F F. Couple Cover(组合计数)的更多相关文章
- Codeforces 932E Team work 【组合计数+斯特林数】
Codeforces 932E Team work You have a team of N people. For a particular task, you can pick any non-e ...
- bzoj 2281 [Sdoi2011]黑白棋(博弈+组合计数)
黑白棋(game) [问题描述] 小A和小B又想到了一个新的游戏. 这个游戏是在一个1*n的棋盘上进行的,棋盘上有k个棋子,一半是黑色,一半是白色. 最左边是白色棋子,最右边是黑色棋子,相邻的棋子颜色 ...
- BZOJ 4555: [Tjoi2016&Heoi2016]求和 [分治FFT 组合计数 | 多项式求逆]
4555: [Tjoi2016&Heoi2016]求和 题意:求\[ \sum_{i=0}^n \sum_{j=0}^i S(i,j)\cdot 2^j\cdot j! \\ S是第二类斯特林 ...
- BZOJ 4555: [Tjoi2016&Heoi2016]求和 [FFT 组合计数 容斥原理]
4555: [Tjoi2016&Heoi2016]求和 题意:求\[ \sum_{i=0}^n \sum_{j=0}^i S(i,j)\cdot 2^j\cdot j! \\ S是第二类斯特林 ...
- 【BZOJ5491】[HNOI2019]多边形(模拟,组合计数)
[HNOI2019]多边形(模拟,组合计数) 题面 洛谷 题解 突然特别想骂人,本来我考场现切了的,结果WA了几个点,刚刚拿代码一看有个地方忘记取模了. 首先发现终止态一定是所有点都向\(n\)连边( ...
- [总结]数论和组合计数类数学相关(定理&证明&板子)
0 写在前面 0.0 前言 由于我太菜了,导致一些东西一学就忘,特开此文来记录下最让我头痛的数学相关问题. 一些引用的文字都注释了原文链接,若侵犯了您的权益,敬请告知:若文章中出现错误,也烦请告知. ...
- 【Luogu4931】情侣?给我烧了! 加强版(组合计数)
[Luogu4931]情侣?给我烧了! 加强版(组合计数) 题面 洛谷 题解 戳这里 忽然发现我自己推的方法是做这题的,也许后面写的那个才是做原题的QwQ. #include<iostream& ...
- 【Luogu4921】情侣?给我烧了!(组合计数)
[Luogu4921]情侣?给我烧了!(组合计数) 题面 洛谷 题解 很有意思的一道题目. 直接容斥?怎么样都要一个平方复杂度了. 既然是恰好\(k\)对,那么我们直接来做: 首先枚举\(k\)对人出 ...
- [ZJOI2010]排列计数 (组合计数/dp)
[ZJOI2010]排列计数 题目描述 称一个1,2,...,N的排列P1,P2...,Pn是Magic的,当且仅当2<=i<=N时,Pi>Pi/2. 计算1,2,...N的排列中有 ...
随机推荐
- PHP验证码显示不出来
PHP验证码显示不出来 验证码图片显示不出来,原因一般有三种(网上基本一致这几种原因): (1)php没有安装gd2模块,可以使用phpinfo()函数查看. (2)代码很可能是使用了像editpul ...
- android图片上传
package com.example.center; import java.io.ByteArrayOutputStream;import java.io.InputStream; import ...
- compose.yml模板文件
默认的模板文件名称为 docker-compose.yml,格式为 YAML 格式. 示例: version: " services: webapp: image: examples/web ...
- android apk程序升级
1 .设置apk版本号 Androidmanifest.xml <manifest xmlns:android="http://schemas.android.com/apk/res/ ...
- Elixir与编辑器安装
安装 Elixir 每个操作系统的安装说明可以在 elixir-lang.org 网站上 Installing Elixir 部分找到. 安装后你可以很轻松地确认所安装的版本. ~$:elixir - ...
- 快速掌握RabbitMQ(四)——两种消费模式和QOS的C#实现
本篇介绍一下RabbitMQ中的消费模式,在前边的所有栗子中我们采用的消费者都是EventingBasicConsumer,其实RabbitMQ中还有其他两种消费模式:BasicGet和QueueBa ...
- RED HAT 7 性能监控工具
https://access.redhat.com/documentation/zh-CN/Red_Hat_Enterprise_Linux/7/html/Performance_Tuning_Gui ...
- pnputil
http://mb.yidianzixun.com/article/0FYSZgnB?s=mb&appid=mibrowser C:\Users\Administrator>pnputi ...
- js -- 监听窗口的大小变化
- 《从零開始学Swift》学习笔记(Day 61)——Core Foundation框架之内存管理
原创文章,欢迎转载. 转载请注明:关东升的博客 在Swift原生数据类型.Foundation框架数据类型和Core Foundation框架数据类型之间转换过程中,尽管是大部分是能够零开销桥接,零开 ...