Searching with Quantum Computers

int random();  /* random(N) returns random number between 0 and (N-1) */ 
int f();       /* f(r) is an arbitrary binary function that returns 1 only  
                 for a single value of r, for all other values of r it returns 0 */ 
main() 
{ 
   int i, r, answer = -1; 
   r = random(N); 
   for(i = 0; i < N; i++) 
   { 
       if (f(r) == 1) answer = r; 
       r = random(N); 
    } 
    print(answer); 
} 

Figure 2: Classical probabilistic program.