exBSGS模板
题目bzoj2480，bzoj1467，贴个板子上来吧
1 program j01; 2 const mo=1000007; 3 var head:array[0..mo]of int64; 4 hash,next,data:array[0..mo]of int64; 5 a,b,p,tt:int64; 6 7 function gcd(a,b:int64):int64; 8 begin 9 if b=0 then exit(a) else exit(gcd(b,a mod b)); 10 end; 11 12 function pow(a,i,mm:int64):int64; 13 var y:int64; 14 begin 15 if i=0 then exit(1); 16 y:=pow(a,i div 2,mm) mod mm; 17 y:=y*y mod mm; 18 if i mod 2=1 then y:=y*a mod mm; 19 exit(y); 20 end; 21 22 procedure push(i,w:int64); 23 var x:int64; 24 begin 25 x:=i mod mo; 26 inc(tt); 27 hash[tt]:=i;data[tt]:=w; 28 next[tt]:=head[x]; 29 head[x]:=tt; 30 end; 31 32 function find(i:int64):int64; 33 var j:int64; 34 begin 35 j:=head[i mod mo]; 36 while j>0 do 37 begin 38 if hash[j]=i then exit(data[j]); 39 j:=next[j]; 40 end; 41 exit(-1); 42 end; 43 44 procedure solve; 45 var i:longint; 46 n,now,tmp,x,m,d,cnt,t:int64; 47 begin 48 a:=a mod p;b:=b mod p; 49 if b=1 then 50 begin 51 writeln(0);exit; 52 end; 53 cnt:=0;t:=1; 54 while true do 55 begin 56 d:=gcd(a,p); 57 if d=1 then break; 58 if b=t then 59 begin 60 writeln(cnt);exit; 61 end; 62 if not(b mod d=0) then 63 begin 64 writeln('No Solution');exit; 65 end; 66 p:=p div d;b:=b div d;t:=(t*a div d)mod p; 67 inc(cnt); 68 end; 69 tt:=0;fillchar(head,sizeof(head),0); 70 m:=trunc(sqrt(p))+1;b:=b mod p; 71 now:=b;push(now,0); 72 for i:=1 to m do 73 begin 74 now:=now*a mod p; 75 push(now,i); 76 end; 77 tmp:=pow(a,m,p); 78 now:=t; 79 for i:=1 to m do 80 begin 81 now:=now*tmp mod p; 82 x:=find(now); 83 if x>-1 then 84 begin 85 writeln(i*m-x+cnt); 86 exit; 87 end; 88 end; 89 writeln('No Solution'); 90 end; 91 92 begin 93 while true do 94 begin 95 readln(a,p,b); 96 if (a=0)and(b=0)and(p=0) then break; 97 solve; 98 end; 99 end.
