bzoj1303

首先找到b的位置x，要求满足b为中位数的数列
把比b大的设为1，比b小设为-1
则数列满足条件则x 左边的的和+x右边的和=0 
然后应该就很好搞了

 var a,l,r,s:array[..] of longint;
     i,n,m,x,k,ans:longint;
 begin
   readln(n,m);
   for i:= to n do
   begin
     read(x);
     if x=m then k:=i
     else if x>m then a[i]:=
     else a[i]:=-;
   end;
   l[n]:=;
   r[n]:=;
   for i:=k- downto  do
   begin
     s[i]:=s[i+]+a[i];
     inc(l[s[i]+n]);
   end;
   for i:=k+ to n do
   begin
     s[i]:=s[i-]+a[i];
     inc(r[s[i]+n]);
   end;
   for i:= to *n- do
     ans:=ans+l[i]*r[*n-i];
   writeln(ans);
 end.