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ID    SOURCE    SCORE1    SCORE2    SCORE3    .....    SCOREN
66521    SRC1        12        34        27            67
88921    SRC2        34        56        59            88
66524    SRC1        56        66    
3341    SRC1        44        59        67

print join " ",  reverse split foreach  
    map  { $_->[0] } 
    sort { $a->[1]<=>$b->[1] || $a->[0] <=> $b->[0] } 
    map  { [ $_ , (split)[-1] ] } 
    grep { /SRC1/ } <> ;