Counting Point Mutations
Given two strings s and t of equal length, the Hamming distance between s and t, denoted dH(s, t), is the number of corresponding symbols that differ in s and t.
Example: The Hamming distance between these two strings below is 7. Mismatched symbols are colored red.
Given: Two DNA strings s and t of equal length (not exceeding 1 kbp).
Return: The Hamming distance dH(s, t).