C3: Multi-Controlled X

Problem Statement

Using only Clifford gates and $CCX$ gate,

implement an oracle $U$ satisfying the following on a quantum circuit $\mathrm{qc}$ with $7$ qubits.

For any quantum state $\ket{\psi}_{5}$,

Here, $CCCCX(4)$ denotes the 4-controlled $X$ gate with qubit 5 as the target qubit.

Constraints

• Only Clifford gates and $CCX$ gate can be used.
• The submitted code must follow the specified format:

from qiskit import QuantumCircuit
 
 
def solve() -> QuantumCircuit:
    qc = QuantumCircuit(7)
    # Write your code here:
 
    return qc