Algorithm 2 Correct two consecutive deletion symbols

Input:  $n,d,a,e,\mathit{y}={\mathit{c}}_j^{n-2}\in {\mathbb{F}}_4^{n-2}$. Output:  $\mathit{c}=(c_1,c_2,\dots ,c_n)\in C(n,4)$.  1:$c_j+c_{j+1}=e-{\sum }_{i=j}^{n-2}{y}_i \mathrm{mod} 4$.  2:Get the binary sequence $0{\mathit{x}}_j^{n-2}$ and the run-length vector $\mathit{r}\prime \prime$ of $0{\mathit{x}}_j^{n-2}$.  3:Get the total number of elements of $\mathit{r}\prime \prime$ as $\parallel \mathit{r}\prime \prime \parallel$.  4:$\Delta$ = $d-Rsyn\left(0{\mathit{x}}_j^{n-2}\right) \mathrm{mod} 2n$.  5:Set $j=1$.  6:if  $\Delta \ge 2\parallel \mathit{r}\prime \prime \parallel$ then  7:   while $j\le n-1$ do  8:     if mod$(\Delta ,2)=1$ then  9:        if $2k_{0{\mathit{x}}_j^{n-2}}(j-1)+2(n-j)+1=\Delta$ then  10:          $x_j={\overline{x}}_{j-1}$; $x_{j+1}=x_{j-1}$  11:          $\mathit{c}$ = del_correct2$(n,a,\mathit{y},j,x_j,x_{j+1},c_j$+$c_{j+1})$  12:        else  13:          $j\leftarrow j+1$  14:        end if  15:     else  16:        if $2k_{0{\mathit{x}}_j^{n-2}}(j-1)+2(n-j)=\Delta$ then  17:          $x_j={\overline{x}}_{j-1}$; $x_{j+1}={\overline{x}}_{j-1}$  18:          $\mathit{c}$ = del_correct2$(n,a,\mathit{y},j,x_j,x_{j+1},c_j$+$c_{j+1})$  19:        else  20:          $j\leftarrow j+1$  21:        end if  22:     end if  23:   end while  24:else  25:   while $j\le n-1$ do  26:     if mod$(\Delta ,2)=1$ then  27:        if $2k_{0{\mathit{x}}_j^{n-2}}(j-1)+1=\Delta$ then  28:          $x_j=x_{j-1}$; $x_{j+1}={\overline{x}}_{j-1}$  29:          $\mathit{c}$ = del_correct2$(n,a,\mathit{y},j,x_j,x_{j+1},c_j$+$c_{j+1})$  30:        else  31:          $j\leftarrow j+1$  32:        end if  33:     else  34:        if $2k_{0{\mathit{x}}_j^{n-2}}(j-1)=\Delta$ then  35:          $x_j=x_{j-1}$; $x_{j+1}=x_{j-1}$  36:          $\mathit{c}$ = del_correct2$(n,a,\mathit{y},j,x_j,x_{j+1},c_j$+$c_{j+1})$  37:        else  38:          $j\leftarrow j+1$  39:        end if  40:     end if  41:   end while  42:end if