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Solution: Distinct Subsequences

Explore the dynamic programming approach to solve the problem of counting distinct subsequences of one string that exactly match another. Understand how to use a 1D DP array and reverse iteration to optimize both time and space complexity, gaining skills applicable to coding interviews.

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 ...