better method for calcuting number of qubits required

Author: sagnikpal2004

src/affectedqubits.jl

@@ -10,6 +10,7 @@ affectedqubits(n::NoiseOp) = n.indices
 affectedqubits(g::PauliMeasurement) = 1:length(g.pauli)
 affectedqubits(p::PauliOperator) = 1:length(p)
 affectedqubits(m::Union{AbstractMeasurement,sMRX,sMRY,sMRZ}) = (m.qubit,)
+affectedqubits(m::AbstractReset) = (m.qubit,)
 affectedqubits(v::VerifyOp) = v.indices
 affectedqubits(c::CliffordOperator) = 1:nqubits(c)
 affectedqubits(c::ClassicalXOR) = ()

src/backtrajectory.jl

@@ -215,23 +215,28 @@ end
 #     return backtrajectory(circuit0, nqubits(state))
 # end
 
-function backtrajectory(circuit::Vector{<:AbstractOperation})
-    n = 0
-    for op in circuit
-        if op isa AbstractSingleQubitOperator
-            n = max(n, op.q)
-        elseif op isa AbstractTwoQubitOperator
-            n = max(n, op.q1, op.q2)
-        elseif op isa AbstractMeasurement
-            n = max(n, op.qubit)
-        elseif op isa AbstractReset
-            n = max(n, op.qubit)
-        elseif typeof(op) in [sMRX, sMRY, sMRZ]
-            n = max(n, op.qubit)
-        else
-            error("Unsupported operation: $(typeof(op))")
-        end
-    end
+# function backtrajectory(circuit::Vector{<:AbstractOperation})
+#     n = 0
+#     for op in circuit
+#         if op isa AbstractSingleQubitOperator
+#             n = max(n, op.q)
+#         elseif op isa AbstractTwoQubitOperator
+#             n = max(n, op.q1, op.q2)
+#         elseif op isa AbstractMeasurement
+#             n = max(n, op.qubit)
+#         elseif op isa AbstractReset
+#             n = max(n, op.qubit)
+#         elseif typeof(op) in [sMRX, sMRY, sMRZ]
+#             n = max(n, op.qubit)
+#         else
+#             error("Unsupported operation: $(typeof(op))")
+#         end
+#     end
+
+#     return backtrajectory(circuit, n)
+# end
 
+function backtrajectory(circuit::Vector{<:AbstractOperation})
+    n = maximum(Iterators.flatten(affectedqubits.(circuit)))
     return backtrajectory(circuit, n)
 end