Beautiful Strings

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A binary string is said to be *beautiful*, if the count of "$01$" substrings in the string is equal to that of "$10$" substrings. Chef has a binary string $S$. Chefina asked him to find the count of **non-empty** *beautiful* subsequences of the string $S$. Since the answer can be huge, print it modulo $10^9 + 7$. Note that, a subsequence is obtained by deletion of several (possibly zero) charact

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solution.cppC++17

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