Before revision:  Our /}\eps proof of privacy for this mechanism relies on a novel coupling technique that is of independent theoretical interest .
After revision:  Our /}\eps) is approximately differentially private. Compared to the previous peeling approach of running Report Noisy Max k times, the oneshot Laplace mechanism only adds noises and computes the top k elements once, hence much more efficient for large k. In addition, our proof of privacy for this mechanism relies on a novel coupling technique that is of independent theoretical interest .