noi1_13_41[判断元素是否存在]

Posted 2020-08-12 love_saber

简单的dfs。不必考虑时间。瞬秒。

var s,s1,s2:string;
    k,n,m:longint;
procedure go(k:longint);
begin
 if k=m then begin
              write(‘YES‘);
              halt;
             end;
 if k>m then exit;
 go(2*k+1);
 go(3*k+1);
end;
begin
 readln(s);
 k:=pos(‘,‘,s);
 s1:=copy(s,1,k-1);
 delete(s,1,k);
 s2:=s;
 val(s1,n);
 val(s2,m);
 go(n);
 write(‘NO‘);
end.