perl, 68 bytes

Result

AC

Duration

982ms

Code [DL]

$_=`dd`;/T/;s/(?<=\n.{$-[0]}) /#/g;s/(?<=K) */"#"x length$&/ge;print

stdin

                                           T      
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                      K           

stdout

                                           T      
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                                      K#####      

stderr

4+1 records in
4+1 records out

strace