kmp模式匹配算法的pascal实现

{  Implementation of KMP Algorithm}PROGRAM Impl_KMP;

USES    CRT;

CONST     MAX_STRLEN = 255;

VAR   next         : array [ 1 .. MAX_STRLEN ] of integer;   str_s, str_t : string;   int_i        : integer;

Procedure get_nexst( t : string );Var   j, k : integer;Begin     j := 1; k := 0;     while j < Length(t) do     begin          if ( k = 0 ) or ( t[j] = t[k] ) then          begin               j := j + 1; k := k + 1;               next[j] := k;          end          else k := next[k];     end;End;

Function index( s : string; t : string ) : integer;Var   i, j : integer;Begin     get_next(t);     index := 0;     i := 1; j := 1;     while ( i <= Length(s) ) and ( j <= Length(t) ) do     begin          if ( j = 0 ) or ( s[i] = t[j] ) then          begin               i := i + 1; j := j + 1;          end          else j := next[j];          if j > Length(t) then index := i - Length(t);     end;End;

BEGIN     ClrScr;     Write('s = ');     Readln(str_s);     Write('t = ');     Readln(str_t);     int_i := index( str_s, str_t );     if int_i <> 0 then     begin          Writeln( 'Found ', str_t, ' in ', str_s, ' at ', int_i, '.' );     end     else         Writeln( 'Cannot find ', str_t, ' in ', str_s, '.' );END.

index函数用于模式匹配，t是模式串，s是原串。返回模式串的位置，找不到则返回0