Two product codes are compared ignoring hyphens (-). Given strings a and b, return their longest common prefix with hyphens removed, as a string.
Examples
Input: a = "data-base", b = "da-tab"
Output: "datab"
Explanation: without hyphens they read "database" and "datab".
Input: a = "x-y-z", b = "xz"
Output: "x"
Constraints
0 <= len(a), len(b) <= 10**5- Target: O(len(a) + len(b)) time; do not build hyphen-free copies of the inputs.
Goals
- Run two independent pointers that each skip unwanted characters
- Stop at the first real mismatch or when either string ends