Practice String Transformation
Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.
Problem Statement
s and t have the same length n. One operation chooses a suffix of length from 1 through n - 1 and moves it to the front, preserving the order within both pieces. Return how many sequences of exactly k operations turn s into t, modulo 10^9 + 7.
Source: String Transformation on LeetCode. Use the original task for its coding environment and submissions.
Examples
# Example 1
Input
s = "abcd", t = "cdab", k = 2
Output
2
# Example 2
Input
s = "ababab", t = "ababab", k = 1
Output
2
Constraints
2 <= s.length <= 5 * 10^5
1 <= k <= 10^15
s.length == t.length
s and t consist of only lowercase English alphabets.
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