bm模式匹配算法（BM pattern matching algorithm）.docVIP

bm模式匹配算法（BM pattern matching algorithm） * Function: int* MakeSkip (char * int) Objective: to do preprocessing according to the bad character rule, the establishment of a bad character Parameter: Ptrn = string P PLen = P pattern string length Return： Table int* - bad character * / Int* MakeSkip (char *ptrn, int pLen) { Int i; / / for the establishment of bad character, apply 256 int space /*PS: reason to apply for 256, because a character is 8, So the 8 characters might have 2 or 256 different situations. Int = *skip (int*) malloc (256*sizeof (int)); If (skip = NULL) { Fprintf (stderr, malloc failed!); Return 0; } / / initialize the bad character table, 256 units are all initialized to pLen For (I = 0; I 256; i++) { * (skip+i) = pLen; } / / given in the table need an assignment unit assignment, does not appear in the pattern string character is no longer the assignment While (pLen! = 0) { * (skip+ (unsigned char) *ptrn++ = pLen--); } Return skip; } * Function: int* MakeShift (char * int) Objective: according to the good suffix rule preprocessing, establish a good suffix table Parameter: Ptrn = string P PLen = P pattern string length Return： Int* - the good suffix table * / Int* MakeShift (char* ptrn, int pLen) { For the good suffix list for the pLen / int space Int = *shift (int*) malloc (pLen*sizeof (int)); Int *sptr = Shift + pLen - 1; / / convenience to the good suffix table assignment index Char *pptr = ptrn + pLen - 1; / / record suffix table boundary position indicator Char c; If (shift = NULL) { Fprintf (stderr, malloc failed!); Return 0; } * (C = ptrn + pLen - 1); / / the last character of the pattern string to save, because it is used repeatedly *sptr = 1; / / to the last character as the boundary, determine the moving distance of 1 Pptr--; / / boundary moves to the last second characters (this sentence I add up, because I do not feel that there will be added to BUG, we try to abcdd, that is the end of the two repeated situation) While (sptr--! = shift)