  Present-day, noisy, small or intermediate-scale quantum processors---although
far from fault-tolerant---support the execution of heuristic quantum
algorithms, which might enable a quantum advantage, for example, when applied
to combinatorial optimization problems. On small-scale quantum processors,
validations of such algorithms serve as important technology demonstrators. We
implement the quantum approximate optimization algorithm (QAOA) on our hardware
platform, consisting of two superconducting transmon qubits and one
parametrically modulated coupler. We solve small instances of the NP-complete
exact-cover problem, with 96.6% success probability, by iterating the algorithm
up to level two.
