bash-busybox, 48 bytes

Result

AC

Duration

1299ms

Code [DL]

sed '1h
${:1
x
s/ $//
t1
x
:2
s/K /KK/
t2
h
}
g'

stdin

                                                 T
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                        K                         

stdout

                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                        KKKKKKKKKKKKKKKKKKKKKKKKKK

stderr

strace