Algorithm 1: Bernstein and Vazirani [19,20]

Proceed with the following steps. Prepare an n-qubit query register and an additional answer qubit in the state $\left|0^n\right.〉\left|1\right.〉$. Apply the Walsh-Hadamard transform to the query register and the output qubit. Apply the oracle. Apply the Walsh-Hadamard transform to the query register. Measure the query register in the computational basis.   The measurement in the last step will reveal the secret string s.