You are given two strings s and t of equal length n. You can perform the following operation on the string s:
s of length l where 0 < l < n and append it at the start of s.s = 'abcd' then in one operation you can remove the suffix 'cd' and append it in front of s making s = 'cdab'.You are also given an integer k. Return the number of ways in which s can be transformed into t in exactly k operations.
Since the answer can be large, return it modulo 109 + 7.
\n
Example 1:
\n\n\nInput: s = "abcd", t = "cdab", k = 2\nOutput: 2\nExplanation: \nFirst way:\nIn first operation, choose suffix from index = 3, so resulting s = "dabc".\nIn second operation, choose suffix from index = 3, so resulting s = "cdab".\n\nSecond way:\nIn first operation, choose suffix from index = 1, so resulting s = "bcda".\nIn second operation, choose suffix from index = 1, so resulting s = "cdab".\n\n\n
Example 2:
\n\n\nInput: s = "ababab", t = "ababab", k = 1\nOutput: 2\nExplanation: \nFirst way:\nChoose suffix from index = 2, so resulting s = "ababab".\n\nSecond way:\nChoose suffix from index = 4, so resulting s = "ababab".\n\n\n
\n
Constraints:
\n\n2 <= s.length <= 5 * 1051 <= k <= 1015s.length == t.lengths and t consist of only lowercase English alphabets.t can be only constructed if it is a rotated version of string s.",
"Use KMP algorithm or Z algorithm to find the number of indices from where s is equal to t.",
"Use Dynamic Programming to count the number of ways."
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