What are the R1CS constraints of a cryptocurrency system like ZCash?

This was answered fairly well by the stackexchange post: https://crypto.stackexchange.com/questions/65927/what-is-the-precise-np-statement-of-zcash

In particular, some high level constraints are:

1. For every shielded transfer, the input values sum to the output values 2. The sender proves that they have the spending keys for the input 3. The private sending keys are linked to a signature over the whole transaction in such a way that it cannot be forged by someone who does not know the keys