Solution: Count the Number of Good Subsequences
Explore how to count the number of good subsequences where each character has equal frequency in a string. Learn dynamic programming techniques to efficiently calculate factorials and modular inverses to handle combinations. Understand how to apply binomial coefficients and modular arithmetic to find the solution, gaining skills useful in coding interviews and algorithm challenges.
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Statement
Count and return the number of good subsequences in the given string s. You may return the modulo
A subsequence is a sequence formed from another sequence by deleting some or no elements while keeping the order of the remaining elements unchanged.
A good subsequence is a subsequence of a string if it is not empty and the frequency of each character is the same.
Constraints:
s.lengthswill only contain ...