Problem26 - commit file
Problem32 - done
Problem33 - done
Problem34 - done
Problem35 - done
Problem36 - done
bug fix
Problem37 - done
Problem38 - done
Problem39 - done
Problem40 - done
Problem40 - improve performance
Problem41 - done
Problem46 - done
Problem47 - done
Problem48 - done
Problem49 - done
Problem50 - make aux funcs
Problem50 - done using external heap