Typo Repair Bill

medium

A print shop fixes botched engravings character by character. Each repair operation costs one billable unit: insert a character, delete a character, or replace one character with another.

Given the engraved string current and the string the customer ordered, target, return the minimum number of operations to turn current into target.

Example 1

in current = "horse", target = "ros"

out 3

Replace h→r, delete the r that follows, delete the e.

Example 2

in current = "kitten", target = "sitting"

out 3

k→s, e→i, insert g.

Constraints

· 0 <= len(current), len(target) <= 50
· lowercase letters only