Significance:
Biology is noisy — sequencing errors, natural polymorphism, and imperfect regulatory motifs mean exact string matching (Problem 6) is often too strict for real use. Approximate matching, allowing up to `d` mismatches, is exactly how tools like Bowtie/BWA locate a read's true genomic origin despite sequencing errors, and how transcription-factor binding sites are located even though they tolerate some sequence degeneracy.
Statement
Given a DNA string `s`, a motif `t`, and an integer `d`, find all starting positions (1-based) in `s` where a substring of length `len(t)` matches `t` with **at most `d` mismatches** (measured as Hamming distance).