This paper presents an improved Grover searching algorithm which can automatically control the iterative processing when the number of target states is unknown.The probability of success of Grover searching algorithm depends on the number of iteration times and the number of the time of iterations relies on the number of target states.Therefore

it is hard to get the target state with high probability when the number of target states is unknown.To this question

the time complexity of conventional solution is high and the answer is non-deterministic.This paper shows an improved Grover searching algorithm

which is based on the sign for the phases of superposition state.Compared to existing research results

this algorithm can always stop the Grover iterations when the number of iteration times is optimal by the cost where just one more gate

and one more time Oracle call are needed to judge the sign of phase.