Copied input vector to not modify the users input

Author: M-J-Hochreiter

include/mqt-core/algorithms/StatePreparation.hpp

@@ -37,6 +37,6 @@ namespace qc {
  * not a power of two.
  **/
 [[nodiscard]] auto
-createStatePreparationCircuit(std::vector<std::complex<double>>& amplitudes,
+createStatePreparationCircuit(const std::vector<std::complex<double>>& amplitudes,
                               double eps = 1e-10) -> QuantumComputation;
 } // namespace qc

src/algorithms/StatePreparation.cpp

@@ -268,9 +268,11 @@ gatesToUncompute(std::vector<std::complex<double>>& amplitudes,
 }
 
 auto createStatePreparationCircuit(
-    std::vector<std::complex<double>>& amplitudes, double eps)
+    const std::vector<std::complex<double>>& amplitudes, double eps)
     -> QuantumComputation {
 
+  auto amplitudesCopy = amplitudes;
+
   if (!isNormalized(amplitudes, eps)) {
     throw std::invalid_argument{
         "Using State Preparation with Amplitudes that are not normalized"};
@@ -284,7 +286,7 @@ auto createStatePreparationCircuit(
   }
   const auto numQubits = static_cast<size_t>(std::log2(amplitudes.size()));
   QuantumComputation toZeroCircuit =
-      gatesToUncompute(amplitudes, numQubits, eps);
+      gatesToUncompute(amplitudesCopy, numQubits, eps);
 
   // invert circuit
   toZeroCircuit.invert();