Algorithm 1 Discard matching strategy.

Input: Current $2L$ extended path $\{{\mathrm{PME}}_l^{(i-1)},l=1,2,\dots ,2L\}$, IPS output $\widehat{\mathit{d}}$ Output: L survival paths PM $\{{\mathrm{PM}}_l^i,l=1,2,\dots ,L\}$ 1: $cnt\_pm=1$ 2: for $s=1,2,\dots ,2L$ do 3:    if ${\widehat{d}}_l=1\mathrm{and}cnt\_pm\le L$ then 4:     ${\mathrm{PM}}_{cnt\_pm}^i={\mathrm{PME}}_s^{(i-1)}$ 5:      $cnt\_pm=cnt\_pm+1$ 6:    end if 7: end for 8: if $\Omega <L$ then 9:    for $s=1,2,\dots ,2L$ do 10:      if ${\widehat{d}}_l=0\mathrm{and}cnt\_pm\le L$ then 11:         ${\mathrm{PM}}_{cnt\_pm}^i={\mathrm{PME}}_s^{(i-1)}$ 12:         $cnt\_pm=cnt\_pm+1$ 13:      end if 14:    end for 15: end if