Given a string S, find the number of different non-empty palindromic subsequences in S, and return that number modulo 10^9 + 7. A subsequence of a string S is obtained by deleting 0 or more characters ...

# and return that number modulo 10^9 + 7. # A subsequence of a string S is obtained by deleting 0 or more characters from S. # A sequence is palindromic if it is equal to the sequence reversed. # Two ...