With what loop to implement string comparison?

Question

Python

On some forum I saw a task for freelance, the project had already been closed, but I was very interested in how the task was being solved.
The bottom line is that the file contains many lines of the following content:

t1 1 2 3 
t1 4 5 2
t1 2 3 4
t2 0 2 2

And the output is a file with the result:

t1 2 2 3
t2 1 1 1

That is, lines with the same beginning are compared:

t1 1 2 3 
t1 4 5 2
t1 2 3 4

And in response, the line number is written where the largest number in the index is.
Can you please explain how to solve this?
It is very interesting how this is implemented.