传送门 题目 \[ \begin{aligned} &f_n=c^{2*n-6}f_{n-1}f_{n-2}f_{n-3}&\\ \end{aligned} \] 思路 我们通过迭代发现\(f_n\)其实就是由\(c^{t_1},f_1^{t_2},f_2^{t_3},f_3^{t_4}\)相乘得到,因此我们可以分别用矩阵快速幂求出\(t_1,t_2,t_3,t_4\),最后用快速幂求得答案. 对于\(n<=3\)的我们直接输出即可,\(n>3\)的我们先将\(n\)减去\(3…

https://codeforces.com/contest/1106/problem/F 题意 数列公式为\(f_i=(f^{b_1}_{i-1}*f^{b_2}_{i-2}*...*f^{b_k}_{i-k})\)mod\(P\),给出\(f_{1}...f_{k-1}\)和\(f_{n}\),求\(f_{k}\),其中\(P\)等于998244353 题解 3是998244353的离散对数,所以\(f^{b_1}_{i-1} \equiv 3^{h_i*b_1}(modP)\),怎么求离散…

D. GukiZ and Binary Operations time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output We all know that GukiZ often plays with arrays. Now he is thinking about this problem: how many arrays a, of l…

D. Tanya and Password Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/508/problem/D Description While dad was at work, a little girl Tanya decided to play with dad's password to his secret database. Dad's password is a stri…

D. Recover it! Authors guessed an array aa consisting of nn integers; each integer is not less than 22 and not greater than 2⋅1052⋅105. You don't know the array aa, but you know the array bb which is formed from it with the following sequence of oper…

Codeforces Round #566 (Div. 2) A Filling Shapes 给定一个 \(3\times n\) 的网格,问使用 这样的占三个格子图形填充满整个网格的方案数 如果 \(n\) 是奇数,那么显然无解,否则考虑每个 \(3\times2\) 的方格正好能塞下两个这玩意而且必须这样塞进去,方案数为 \(2\),因此答案为 \(2^{n/2}\) B Plus from Picture 给定一个 \(h\times w\) 的矩阵,每个元素为 "." 或者…

时间\(9.05\)好评 A Filling Shapes 宽度为\(3\),不能横向填 考虑纵向填,长度为\(2\)为一块,填法有两种 如果长度为奇数则显然无解,否则\(2^{n/2}\) B Plus from Picture 找到最靠上的十字轮廓(没有则直接无解),删掉后判断有无多余 C Beautiful Lyrics 以元音数量及最后的元音(如果没有元音的那些分别赋不同的负数)为一二关键词 开两个栈,代表诗头和诗尾 排序后,得到的以第一关键字的块,尽量把每一对放到诗尾,因为诗尾的也可以…

链接: https://codeforces.com/contest/1182/problem/C 题意: You are given n words, each of which consists of lowercase alphabet letters. Each word contains at least one vowel. You are going to choose some of the given words and make as many beautiful lyric…

链接: https://codeforces.com/contest/1182/problem/B 题意: You have a given picture with size w×h. Determine if the given picture has a single "+" shape or not. A "+" shape is described below: A "+" shape has one center nonempty c…

链接: https://codeforces.com/contest/1182/problem/A 题意: You have a given integer n. Find the number of ways to fill all 3×n tiles with the shape described in the picture below. Upon filling, no empty spaces are allowed. Shapes cannot overlap. This pict…