If both of them are equal B is not cheaper

Well my ouptput is correct and the expected output is wrong so I guess that counts as an "issue"

"my code does not work" is not a valid kata issue.

Please read through this FAQ and see if it helps: https://docs.codewars.com/training/troubleshooting

string = xopDjUdgHGJPoaUXWSAN

indices = {17, 4, 7, 45, 18, 9, 13, 14, 12, 4}

submitted = xopDJUdGHGJPOAUXWSAN

expected = xopDJUdGHGJPO

I tried this kata in C and one of the test cases fails.