如何将与data.frame单元格一起工作的函数应用到data.frame列

This question is the adaptation of a prior question I felt I asked in an unclear way. I am checking whether columns V1 and V2 have common codes by row. Codes are separated by a forward slash "/". The function below should take one cell from V1 and one cell from V2 on the same row and should transform them into vectors. Each element of a vector is one code. Then the function should check whether the two vectors obtained have elements in common. These elements initially are 4-digit codes. If there is any 4-digit code that matches between the two vectors, the function should return 4. If there are no elements in common, the function should reduce the number of digits of each code and then check again. Every time that the function reduces the number of digits, it also reduces the score it returns at the end. I would like the value returned by the function to be written in a column of my choice.This question is the adaptation of a prior ques