Protecting Check-In Data Privacy in Blockchain Transactions with Preserving High Trajectory Pattern Utility

Algorithm 3

The generalized location search algorithm.

Input: distance index D-index, query distance R, any location ;

Output: location queue L.

1. L=;

2. pos =1, end =lens (D-index []);

3. While (pos<end) do

4.  mid=(post+end)/2;

5. if D-index[mid]<then

6.   pos=mid+1;

7. else if D-index[mid]>R then

8.   end=mid-1;

9.  else

10.   pos=end=mid;

11. L=D-index [], i∈(1, pos);

12. Return L.