I need some hint on how to adapt grover's algorithm to search the minimum in a database with $N=2^n$ elements in $O(\sqrt{N}\log(N))$ queries with probability of success $\geq 2/3$. I know I can do it by basically choosing randomly a "pivot" and then applying Grover to find a number smaller than that, then update my pivot. But is there something more to it?


1 Answer 1


There is an algorithm by Dürr and Høyer that seems to solve your problem. This algorithm finds the correct answer in $\mathcal{O}(\sqrt{N})$ time with probability $1/2$.

The crux is that they have an oracle which flips the phase of all states with a smaller value than the currently selected one.

  • $\begingroup$ I have seen that, but it's overkill. I am looking for something more naive. $\endgroup$
    – Karl
    Commented Mar 14, 2019 at 14:33
  • 1
    $\begingroup$ @Karl What do you mean by more naive? $\endgroup$
    – cnada
    Commented Mar 14, 2019 at 14:59

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