Palindrome Partition
题意翻译
给定一个串,把串分为偶数段
假设分为了$s1,s2,s3....sk$
求,满足$s_1=s_k,s_2=s_{k-1}......$ 的方案数
题目描述
Given a string $ s $ , find the number of ways to split $ s $ to substrings such that if there are $ k $ substrings $ (p_{1},p_{2},p_{3},...,p_{k}) $ in partition, then $ p_{i}=p_{k-i+1} $ for all $ i $ $ (1<=i<=k) $ and $ k $ is even.
Since the number of ways can be large, print it modulo $ 10^{9}+7 $ .
输入输出格式
输入格式
The only line of input contains a string $ s $ $ (2<=|s|<=10^{6}) $ of even length consisting of lowercase Latin letters.
输出格式
Print one integer, the number of ways of partitioning the string modulo $ 10^{9}+7 $ .
输入输出样例
输入样例 #1
abcdcdab
输出样例 #1
1
输入样例 #2
abbababababbab
输出样例 #2
3
说明
In the first case, the only way to partition the string is $ ab|cd|cd|ab $ .
In the second case, the string can be partitioned as $ ab|b|ab|ab|ab|ab|b|ab $ or $ ab|b|abab|abab|b|ab $ or $ abbab|ab|ab|abbab $ .