算法模板——AC自动机

实现功能——输入N，M，提供一个共计N个单词的词典，然后在最后输入的M个字符串中进行多串匹配（关于AC自动机算法，此处不再赘述，详见：Aho-Corasick 多模式匹配算法、AC自动机详解。考虑到有时候字典会相当稀疏，所以引入了chi和bro指针进行优化——其原理比较类似于邻接表，这个东西和next数组本质上是一致的，只是chi和bro用于遍历某一节点下的子节点，next用于查询某节点下是否有需要的子节点）

  1 type
  2     point=^node;
  3     node=record
  4                ex:longint;st:ansistring;
  5                ct:char;
  6                fat,jump,chi,bro:point;
  7                next:array['A'..'Z'] of point;
  8     end;
  9 var
 10    i,j,k,l,m,n:longint;
 11    head,p:point;
 12    s1,s2:ansistring;
 13 function getpoint:point;inline;
 14          var p:point;c1:char;
 15          begin
 16               new(p);
 17               p^.ex:=0;p^.st:='';
 18               p^.ct:=chr(0);
 19               p^.bro:=nil;p^.chi:=nil;
 20               p^.fat:=nil;p^.jump:=head;
 21               for c1:='A' to 'Z' do p^.next[c1]:=nil;
 22               exit(p);
 23          end;
 24 procedure ins(s1:ansistring;x:longint);inline;
 25           var p:point;s2:ansistring;i:longint;
 26           begin
 27                p:=head;S2:='';
 28                for i:=1 to length(s1) do
 29                    begin
 30                         s2:=s2+s1[i];
 31                         if p^.next[s1[i]]=nil then
 32                            begin
 33                                 p^.next[s1[i]]:=getpoint;
 34                                 p^.next[s1[i]]^.fat:=p;
 35                                 p^.next[s1[i]]^.st:=s2;
 36                                 p^.next[s1[i]]^.ct:=s1[i];
 37                                 p^.next[s1[i]]^.bro:=p^.chi;
 38                                 p^.chi:=p^.next[s1[i]];
 39                            end;
 40                         p:=p^.next[s1[i]];
 41                    end;
 42                if p^.ex=0 then p^.ex:=x;
 43           end;
 44 procedure linkit;inline;
 45           var i,j,k,l,f,r:longint;
 46               d:array[0..10000] of point;
 47               p,p1,p2:point;
 48           begin
 49                f:=1;r:=2;d[1]:=head;
 50                while f<r do
 51                      begin
 52                           p:=d[f]^.chi;
 53                           while p<>nil do
 54                                 begin
 55                                      d[r]:=p;
 56                                      if d[f]<>head then
 57                                         begin
 58                                              p1:=d[f]^.jump;
 59                                              while p1<>head do
 60                                                    begin
 61                                                         if p1^.next[p^.ct]<>nil then break;
 62                                                         p1:=p1^.jump;
 63                                                    end;
 64                                              if p1^.next[p^.ct]<>nil then p^.jump:=p1^.next[p^.ct];
 65                                         end;
 66                                      inc(r);
 67                                      p:=p^.bro;
 68                                 end;
 69                           inc(f);
 70                      end;
 71           end;
 72 procedure fit(s1:ansistring);inline;
 73           var p,p1:point;i:longint;
 74           begin
 75                p:=head;
 76                for i:=1 to length(s1) do
 77                    begin
 78                         if p^.next[s1[i]]=nil then
 79                            begin
 80                                 while (p^.next[s1[i]]=nil) and (p<>head) do p:=p^.jump;
 81                                 if p^.next[s1[i]]<>nil then p:=p^.next[s1[i]];
 82                            end
 83                         else p:=p^.next[s1[i]];
 84                         p1:=p;
 85                         while p1<>head do
 86                               begin
 87                                    if p1^.ex<>0 then writeln('No.',p1^.ex,' ',p1^.st,' From:',i-length(p1^.st)+1);
 88                                    p1:=p1^.jump;
 89                               end;
 90                    end;
 91           end;
 92 begin
 93      readln(n,m);
 94      head:=getpoint;head^.jump:=head;
 95      for i:=1 to n do
 96          begin
 97               readln(s1);
 98               ins(upcase(s1),i);
 99          end;
100      linkit;
101      for i:=1 to m do
102          begin
103               readln(s1);
104               fit(upcase(s1));
105          end;
106 end.
107