很不幸，这题我又被虐了，给个链接http://www.cnblogs.com/g-word/p/3288675.html
1 var p:array[0..20] of longint; 2 f:array[0..200010,0..20] of longint; 3 mx,b,d,v:array[0..200010] of longint; 4 i,j,n,k:longint; 5 ans,s:double; 6 7 function min(a,b:longint):longint; 8 begin 9 if a>b then exit(b) else exit(a); 10 end; 11 12 function ask(l,r:longint):longint; 13 begin 14 k:=trunc(ln(r-l+1)/ln(2)+0.0001); 15 exit(min(f[l,k],f[r-p[k]+1,k])); 16 end; 17 18 begin 19 readln(n); 20 for i:=1 to n do 21 read(d[i]); 22 for i:=1 to n do 23 begin 24 read(b[i]); 25 v[b[i]]:=i; 26 end; 27 for i:=1 to n do 28 d[i]:=v[d[i]]; 29 for i:=1 to n do 30 begin 31 v[d[i]]:=i; 32 if mx[i-1]>d[i] then mx[i]:=mx[i-1] else mx[i]:=d[i]; 33 f[i,0]:=d[i]; 34 end; 35 k:=trunc(ln(n)/ln(2)+0.1); 36 p[0]:=1; 37 for i:=1 to k do 38 p[i]:=p[i-1]*2; 39 for j:=1 to k do 40 for i:=1 to n do 41 if i+p[j]-1<=n then 42 f[i,j]:=min(f[i,j-1],f[i+p[j-1],j-1]) 43 else break; 44 ans:=1; 45 for i:=1 to n-1 do 46 if (i=1) or (v[i]>v[i+1]) then ans:=ans+1+s 47 else if (v[i+1]=v[i]+1) and (mx[v[i]]<=i+1) then s:=s+0.5 48 else if ask(v[i],v[i+1])<i then s:=0; 49 ans:=ans+s; 50 writeln(ans-0.001:0:3); 51 writeln(ans:0:3); 52 writeln(ans+0.001:0:3); 53 end.