Input: The set of undetermined sensors ( ) in Phase 1.
Output: An initial set of sensors ( ) with distances between each other
known.
Step 1: Choose the first element in to be the first element in .
Step 2: Repeat:
   For each element in :
    If it has given distances to all the elements in ,
     add it into .
    End
   End
Algorithm 3: Choose an initial set in Phase 2.