question: private static int postfixLen ( String o1 , String o2 , int prefix ) { int postfix = 0 ; int p1 = o1 . length ( ) , p2 = o2 . length ( ) ; while ( p1 > prefix && p2 > prefix && ( o1 . charAt ( -- p1 ) == o2 . charAt ( -- p2 ) ) ) { ++ postfix ; } return postfix ; }
target:  Compute the postfix length.