Codeforces Round #324 (Div. 2) B
1 second
256 megabytes
standard input
standard output
Kolya loves putting gnomes at the circle table and giving them coins, and Tanya loves studying triplets of gnomes, sitting in the vertexes of an equilateral triangle.
More formally, there are 3n gnomes sitting in a circle. Each gnome can have from 1 to 3 coins. Let's number the places in the order they occur in the circle by numbers from 0 to 3n - 1, let the gnome sitting on the i-th place have ai coins. If there is an integer i (0 ≤ i < n) such that ai + ai + n + ai + 2n ≠ 6, then Tanya is satisfied.
Count the number of ways to choose ai so that Tanya is satisfied. As there can be many ways of distributing coins, print the remainder of this number modulo 109 + 7. Two ways, a and b, are considered distinct if there is index i (0 ≤ i < 3n), such that ai ≠ bi (that is, some gnome got different number of coins in these two ways).
A single line contains number n (1 ≤ n ≤ 105) — the number of the gnomes divided by three.
Print a single number — the remainder of the number of variants of distributing coins that satisfy Tanya modulo 109 + 7.
1
20
2
680
20 ways for n = 1 (gnome with index 0 sits on the top of the triangle, gnome 1 on the right vertex, gnome 2 on the left vertex): 
题意: 输入一个n 3*n个位置 0~3n-1 每个位置的k等于(1,2,3)
若ai + ai + n + ai + 2n ≠ 6 则算做一种情况 问共有多少情况 % 1000000000+9
题解: 计算式子
ans1=3^3n%mod
ans2=7^n%mod
( ans1-ans2)%mod
若 ans1<ans2
则输出(ans1+mod-ans2)%mod
#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>
#include<stack>
#include<cmath>
#define ll __int64
#define pi acos(-1.0)
#define mod 1000000007
using namespace std;
ll n;
ll ans1,ans2;
ll quickmod(ll a,ll b)
{
ll sum=;
while(b)
{
if(b&)
sum=(sum*a)%mod;
b>>=;
a=(a*a)%mod;
}
return sum;
}
int main()
{
scanf("%I64d",&n);
ans1=quickmod(,*n)%mod;
ans2=quickmod(,n)%mod;
if(ans1>=ans2)
printf("%I64d\n",(ans1-ans2)%mod);
else
printf("%I64d\n",(ans1+mod-ans2)%mod);
return ;
}
Codeforces Round #324 (Div. 2) B的更多相关文章
- Codeforces Round #324 (Div. 2)解题报告
---恢复内容开始--- Codeforces Round #324 (Div. 2) Problem A 题目大意:给二个数n.t,求一个n位数能够被t整除,存在多组解时输出任意一组,不存在时输出“ ...
- Codeforces Round #324 (Div. 2) C (二分)
题目链接:http://codeforces.com/contest/734/problem/C 题意: 玩一个游戏,一开始升一级需要t秒时间,现在有a, b两种魔法,两种魔法分别有m1, m2种效果 ...
- Codeforces Round #324 (Div. 2) E. Anton and Ira 贪心
E. Anton and Ira Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/584/probl ...
- Codeforces Round #324 (Div. 2) D. Dima and Lisa 哥德巴赫猜想
D. Dima and Lisa Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/584/probl ...
- Codeforces Round #324 (Div. 2) C. Marina and Vasya 贪心
C. Marina and Vasya Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/584/pr ...
- Codeforces Round #324 (Div. 2) B. Kolya and Tanya 快速幂
B. Kolya and Tanya Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/584/pro ...
- Codeforces Round #324 (Div. 2) A. Olesya and Rodion 水题
A. Olesya and Rodion Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/584/p ...
- Codeforces Round #324 (Div. 2) (哥德巴赫猜想)
题目:http://codeforces.com/problemset/problem/584/D 思路: 关于偶数的哥德巴赫猜想:任一大于2的偶数都可写成两个素数之和. 关于奇数的哥德巴赫猜想:任一 ...
- Codeforces Round #324 (Div. 2) Dima and Lisa 哥德巴赫猜想
原题链接:http://codeforces.com/contest/584/problem/D 题意: 给你一个奇数,让你寻找三个以内素数,使得和为这个奇数. 题解: 这题嘛...瞎比搞搞就好,首先 ...
- Codeforces Round #324 (Div. 2) Marina and Vasya 乱搞推理
原题链接:http://codeforces.com/contest/584/problem/C 题意: 定义$f(s1,s2)$为$s1,s2$不同的字母的个数.现在让你构造一个串$s3$,使得$f ...
随机推荐
- JS - 给String.prototype添加replaceAll方法
String.prototype.replaceAll = function (targetStr, newStr) { var sourceStr = this.valueOf(); while ...
- form表单submit按钮提交页面不跳转
方案一 <html> <body> <form action="" method="post" target="nm_i ...
- 为什么 redis 单线程却能支撑高并发
redis 和 memcached 有什么区别?redis 的线程模型是什么?为什么 redis 单线程却能支撑高并发? 这个是问 redis 的时候,最基本的问题吧,redis 最基本的一个内部原理 ...
- hadoop的shuffle过程
1. shuffle: 洗牌.发牌——(核心机制:数据分区,排序,缓存): shuffle具体来说:就是将maptask输出的处理结果数据,分发给reducetask,并在分发的过程中,对数据按key ...
- python——闰年的判断
写一个程序,判断给定年份是否为闰年. 这样定义闰年的:能被4整除但不能被100整除,或者能被400整除都是闰年. while(1): year = input("请输入一个年份,让我判断一下 ...
- 浅谈XX系统跨平台迁移(测试环境)
一 概述 XX系统目前运行在XX-A的云平台上,计划将其迁移至XX-B的云平台. XX系统是java开发,中间组件涉及nginx+keepalived实现各个业务系统之间的高可用,kafka,zook ...
- B-树 动机与结构
Ps.我们遵循从感性到理性的认知顺序来逐步探索B-树的奥秘,之前经常说的value这里用key(关键码)指代,因为可能存的是字符串,说是value就不合适了. (多图预警!!!建议在WI-FI下观看) ...
- P2680 运输计划(二分+树上差分)
P2680 运输计划 链接 分析: 二分+树上差分. 首先可以二分一个答案,那么所有比这个答案大的路径,都需要减去些东西才可以满足这个答案. 那么减去的这条边一定在所有的路径的交集上. 那么如果求快速 ...
- 世界未解之谜之----------Android Gradle
今天运行项目,运行的debug出来的包竟然是命名过的,但是我的buildTypes里面的debug 并没有执行重命名操作.很奇怪,我的猜测是: 执行buildTypes的时候,虽然是assermdeb ...
- Div处理滚动条问题
1,用div做容器现在已经十分普遍,下面是最基本的代码 <div style="width:50px;height:50px;background-color:blue"&g ...