question: private static float computeSimilarity ( Lane a , Lane b ) { int same = 0 ; int diff = 0 ; int firstCoordinate = Math . max ( a . getFirstNonGapPosition ( ) , b . getFirstNonGapPosition ( ) ) ; int lastCoordinate = Math . min ( a . getLastNonGapPosition ( ) , b . getLastNonGapPosition ( ) ) ; for ( int i = firstCoordinate ; i <= lastCoordinate ; i ++ ) { char cha = a . charAt ( i ) ; char chb = b . charAt ( i ) ; if ( Character . isLetter ( cha ) && Character . isLetter ( chb ) ) { if ( Character . toLowerCase ( cha ) == Character . toLowerCase ( ( chb ) ) ) same ++ ; else diff ++ ; } } return Math . max ( same > 0 ? 1 : 0 , same - 3 * diff ) ; }
target:  computes the similarity of two sequences