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Solution: Distinct Subsequences

Explore how to use dynamic programming to determine the number of distinct subsequences of one string that exactly match another. Understand the optimized 1D DP approach that saves space while iterating through both strings in reverse. Gain insights into time and space complexity for a practical coding interview problem.

Statement

Given two strings, s and t, determine how many distinct subsequences of s match t exactly.

Note: A subsequence is formed by deleting zero or more characters from s without changing the relative order of the remaining characters.

You may assume the result will always fit within a 3232-bit signed integer.

Constraints:

  • 11 \leq s.length, t.length 1000\leq 1000 ...