Implement a quantum oracle on N qubits which implements a function f(x) = x_k, i.e. the value of the function is the value of the k-th qubit.

For an explanation on how the quantum oracles work, see the tutorial blog post.

You have to implement an operation which takes the following inputs:

• an array of qubits x (input register),
• a qubit y (output qubit),
• 0-based index of the qubit from input register K ().

The operation doesn't have an output; the "output" of your solution is the state in which it left the qubits.

Your code should have the following signature:

namespace Solution {
    open Microsoft.Quantum.Primitive;
    open Microsoft.Quantum.Canon;
operation Solve (x : Qubit[], y : Qubit, k : Int) : ()
{
    body
    {
        // your code here
    }
}

}