Issue with the MCX gate using WCFLOBDD backend

[s-jobra]

Hi,
there seems to be some issue with using the MCX gate with the WCFLOBDD backend.
For example, when I run

#include <unordered_map>
#include <string>
#include "quantum_circuit.h"

#define N_SHOTS 1024

int main()
{
    WeightedCFLOBDDQuantumCircuit qc;

    qc.setNumQubits(3);

    qc.ApplyNOTGate(0);
    qc.ApplyNOTGate(1);
    std::vector<long int> controllers = {0, 1};
    qc.ApplyMCXGate(controllers, 2);

    std::unordered_map<std::string, int> measureResults;
    for(int i = 0; i < N_SHOTS; i++) {
        measureResults[qc.Measure()]++;
    }
    for(const auto& pair : measureResults) {
        std::cout << " '" << pair.first << "' : " << pair.second << std::endl;
    }
}

it produces

 '110' : 1024`

when the expected result is '111'. I'm assuming this is because the method WeightedCFLOBDDQuantumCircuit::ApplyMCXGate is defined, however the body of this method is empty.

[cs14b052]

Hi,

Yes. Some gates have not been implemented yet for the WCFLOBDD backend. I plan to do them in the next few weeks. I will at least add "NotImplementedException" so this output doesn't happen.

Please feel free to do it if you want to take a stab at it. However, it might take a few days atleast for me to get to this.

[s-jobra]

Sure, and thanks! I'll see if I can get to it. I just wanted to let you know because I wasn't sure whether it is intentional or not.