Algorithm 2 Sorter

Input: PED: PED sample values that need to be sorted.

Path: Candidate path corresponding to the sample.

K: The number of samples to be retained after sorting.

Output: remPED: Reserved PED value.

remPath: Corresponding candidate path.

1: Function First sorting(PED, Path)

2: PED is divided into 2n heaps according to the characteristics of pre-$\frac{\mathit{n}}{2}$ bits, and the

number of each heap num1(i) is calculated.

3: for i = 1 to 2n do

4:  if num1(i) > K then

5:   The num1 data(as PED2) and the paths(as Path2) are sorted for the second time;

6:  else if num1(i) < K then

7:   The num1 data and the paths as output, i = i + 1;

8:  else

9:   The num1 data and the paths as output;

10:  end if

11:  NEXT i

12: end for

13: Function second sorting(PED2, Path2)

14: PED2 is divided into 2n heaps according to the characteristics of rest-$\frac{\mathit{n}}{2}$ bits, and the

number of each heap num2(i) is calculated.

15: for i = 1 to 2n do

16:  if num2(i) < K then

17:   The num2 data and the paths as output, i = i + 1;

18:  else

19:  The num2 data and the paths as output;

20:  end if

21:  NEXT i

22: end for

23: return