Cp test with 2 questions was conducted first. And from that shortlisted ones had one day hackathon (problem statement) in college campus. Based on performance in hackathon was selected for internship

Cp - You are given a binary string $S$ consisting of '0's and '1's. You need to move all the '1's in the string to the rightmost positions, maintaining their relative order. The movement rules are as follows:

1. To choose a '1', it costs 1 unit.
2. Each step to move a '1' one position to the right costs 1 unit.
3. A '1' cannot move if the position immediately to its right is already occupied by another '1'.
4. You cannot choose a '1' that cannot move. Calculate the maximum time to move all the '1's to the rightmost positions.