d-gdc, 122 bytes

Result

AC

Duration

905ms

Code [DL]

import std.stdio;
void main(){int b,c,d=1;
for(;~(c=getchar());d=++d%51)
  d*=c!=84,
  b=c&1|b&&d,
  putchar(!d|b?99:c);
}

stdin

               T                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
     K                                            

stdout

               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
               c                                  
     ccccccccccc                                  

stderr

strace