  We present Quafu-Qcover, an open-source cloud-based software package designed
for combinatorial optimization problems that support both quantum simulators
and hardware backends. Quafu-Qcover provides a standardized and complete
workflow for solving combinatorial optimization problems using the Quantum
Approximate Optimization Algorithm (QAOA). It enables the automatic modeling of
the original problem as a quadratic unconstrained binary optimization (QUBO)
model and corresponding Ising model, which can be further transformed into a
weight graph. The core of Qcover relies on a graph decomposition-based
classical algorithm, which enables obtaining the optimal parameters for the
shallow QAOA circuit more efficiently. Quafu-Qcover includes a specialized
compiler that translates QAOA circuits into physical quantum circuits capable
of execution on Quafu cloud quantum computers. Compared to a general-purpose
compiler, ours generates shorter circuit depths while also possessing better
speed performance. The Qcover compiler can establish a library of qubits
coupling substructures in real time based on the updated calibration data of
the superconducting quantum devices, ensuring that the task is executed on
physical qubits with higher fidelity. The Quafu-Qcover allows us to retrieve
quantum computer sampling result information at any time using task ID,
enabling asynchronous processing. Besides, it includes modules for result
preprocessing and visualization, allowing for an intuitive display of the
solution to combinatorial optimization problems. We hope that Quafu-Qcover can
serve as a guiding example for how to explore application problems on the Quafu
cloud quantum computers
