POJ 3006(线性筛素数）

线性筛素数……

Program P3006;const   maxn=1000000;var   prime:array[1..maxn] of boolean;   p:array[1..maxn] of longint;   t:longint;   a,d,n:longint;Procedure primeing;var   i,j:longint;begin   fillchar(prime,sizeof(prime),false);   t:=0;   prime[1]:=true;   for i:=2 to maxn do   begin      if not(prime[i]) then      begin         inc(t);         p[t]:=i;      end;      for j:=1 to t do      begin         if p[j]*i>maxn then break;         prime[p[j]*i]:=true;         if i mod p[j]=0 then break;      end;   end;end;begin   primeing;   readln(a,d,n);   while (a+d+n>0) do   begin      while (n>0) do      begin         if not(prime[a]) then dec(n);         inc(a,d);      end;      writeln(a-d);      readln(a,d,n);   end;end.