A14124. String Counting
编程题
普及/提高-
知识点
题目描述
You have $c_1$ letters 'a', $c_2$ letters 'b', ..., $c_{26}$ letters 'z'. You want to build a beautiful string of length $n$ from them (obviously, you cannot use the $i$ -th letter more than $c_i$ times). Each $c_i$ is greater than $\frac{n}{3}$ .
A string is called beautiful if there are no palindromic contiguous substrings of odd length greater than $1$ in it. For example, the string "abacaba" is not beautiful, it has several palindromic substrings of odd length greater than $1$ (for example, "aca"). Another example: the string "abcaa" is beautiful.
Calculate the number of different strings you can build, and print the answer modulo $998244353$ .
A string is called beautiful if there are no palindromic contiguous substrings of odd length greater than $1$ in it. For example, the string "abacaba" is not beautiful, it has several palindromic substrings of odd length greater than $1$ (for example, "aca"). Another example: the string "abcaa" is beautiful.
Calculate the number of different strings you can build, and print the answer modulo $998244353$ .
输入格式
The first line contains one integer $n$ ( $3 \le n \le 400$ ).
The second line contains $26$ integers $c_1$ , $c_2$ , ..., $c_{26}$ ( $\frac{n}{3} < c_i \le n$ ).
The second line contains $26$ integers $c_1$ , $c_2$ , ..., $c_{26}$ ( $\frac{n}{3} < c_i \le n$ ).
输出格式
Print one integer — the number of strings you can build, taken modulo $998244353$ .
输入输出样例
输入 #1
4 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
输出 #1
422500
输入 #2
3 2 2 2 2 2 2 3 3 3 2 2 2 2 2 2 3 3 3 2 2 3 2 2 3 2 2
输出 #2
16900
输入 #3
400 348 322 247 158 209 134 151 267 268 176 214 379 372 291 388 135 147 304 169 149 193 351 380 368 181 340
输出 #3
287489790