If you just want to get a 100% correct, here’s a replay to give you an idea (not describing the algo, some work remaining for you): https://www.codingame.com/replay/490623647
For a score around 320 in total it’s just enumerating all possible numbers. Then taking one of them, reducing the list of candidates based on the answer. Keep trying until you got the right one. That’s pretty quick actually (about 11 attempts for a 10 digit number).
But needs some speed optimizations. I failed with C# and had to convert my code to C++.