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Grokking the Coding Interview Patterns in Python

Solution: Distinct Subsequences

Explore how to use dynamic programming to determine the number of distinct subsequences of one string that match another exactly. Learn the technique to optimize space by reducing a 2D DP table to a 1D array while maintaining correct order and calculate time and space complexity for the solution.

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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:

  • 1≤1 \leq s.length, t.length ≤1000\leq 1000 ...