Fewest Subsequences of a Source String That Concatenate to a Target String

Company: Pinterest

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: hard

Interview Round: Onsite

Overview: Given a source string and a target string, return the fewest subsequences of the source whose concatenation equals the target, or -1 when the target cannot be formed. It tests subsequence matching, greedy reasoning about why a choice is optimal, and an efficient iterative implementation.

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