cobol, 419 bytes

Result

AC

Duration

791ms

Code [DL]

       >>SOURCE FORMAT IS FREE
id division.program-id.a.data division.working-storage section. 1 s pic x(50). 1 p pic x(50). 1 t pic 99. 1 k pic 99. procedure division.accept s.inspect s tallying t for leading " ".b.display s.accept p.move 0 to k.inspect p tallying k for all " ".if k = 50 then go to b end-if.string p(1 : t) "T" into s.inspect s replacing all " " by "*" after initial "K" before initial "T".display s.

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                
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                                 T                
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                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
                                 T                
            K********************T                

stderr

/tmp/code.cbl:2: warning: line not terminated by a newline

strace