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Grokking the Coding Interview Patterns in JavaScript

Number of Ways to Form Target String Given a Dictionary

Understand how to apply dynamic programming to count the number of ways to construct a target string from a set of equal-length words. Learn to follow the rules restricting character selection order and implement a solution that handles large outputs using modular arithmetic.

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Statement

You are given a list of nn strings, words, where each string has the same length mm, and a target string, target, of length tt. A target can be formed using the given words under the following rules:

  • You must build the target from left to right.

  • To form the ith character (0-indexed) ...