Problem finding maximum element index -- How do I do this?

[infinite-pursuits]

I have a circuit with the following piece of code:

cmpresult := api.Cmp(logits[0], logits[1])
ind := api.Select(cmpresult, frontend.Variable(0), frontend.Variable(1))

This gives me the error constraint #3812 is not satisfied: -1 ⋅ 2 != 0 , possibly because I use api.Cmp (can be 0,1, or -1) inside of api.Select which expects 0 or 1 only.

The functionality I want is just to find the index of the maximum element in a 2 element list. Is there an alternate way to implement this without encountering the error?

[ivokub]

You could provide maximum value using a hint, compare this value against all values inside the slice to be less equal than the maximum value (cmpresult = Cmp(values[i], max); AssertIsEqual(cmpresult*(1-cmpresult), 0)). Additionally, you have to show that at least one of the elements is equal to the maximum value, but you can do this by counting the number of cmpresult == 0 and it must be bigger than 0.