树状数组 要一点思考

 1 program hehe;
 2 var
 3  t,n,m,i,j,k:longint;
 4  c:array[0..1000000] of longint;
 5  pre,next,a,x:array[0..50005] of longint;
 6  ans,p,z,y:array[0..200005] of longint;
 7 
 8   procedure sort(l,r:longint);
 9   var
10    zuo,you,mid:longint;
11   begin
12    zuo:=l;
13    you:=r;
14    mid:=y[(l+r)>>1];
15    repeat
16     while y[zuo]<mid do inc(zuo);
17     while y[you]>mid do dec(you);
18     if zuo<=you then
19     begin
20      t:=z[zuo];
21      z[zuo]:=z[you];
22      z[you]:=t;
23      t:=y[zuo];
24      y[zuo]:=y[you];
25      y[you]:=t;
26      t:=p[zuo];
27      p[zuo]:=p[you];
28      p[you]:=t;
29      dec(you);
30      inc(zuo);
31     end;
32    until zuo>you;
33    if l<you then sort(l,you);
34    if zuo<r then sort(zuo,r);
35   end;
36 
37   function lowbit(a:longint):longint;
38   begin
39    exit(a and(-a));
40   end;
41 
42   procedure add(a,b:longint);
43   begin
44    while a<=n do
45    begin
46     x[a]:=x[a]+b;
47     a:=a+lowbit(a);
48    end;
49   end;
50 
51   function find(a:longint):longint;
52   var
53    s:longint;
54   begin
55    s:=0;
56    while a>0 do
57    begin
58     s:=s+x[a];
59     a:=a-lowbit(a);
60    end;
61    exit(s);
62   end;
63 
64 begin
65  readln(n);
66  fillchar(a,sizeof(a),255);
67  for i:=1 to n do
68  begin
69   read(a[i]);
70   pre[i]:=c[a[i]];
71   c[a[i]]:=i;
72   next[pre[i]]:=i;
73  end;
74  read(m);
75  for i:=1 to m do read(z[i],y[i]);
76  for i:=1 to m do p[i]:=i;
77  sort(1,m);
78  for i:=1 to m do
79  begin
80   while j<y[i] do
81   begin
82    inc(j);
83    add(pre[j]+1,1);
84    add(j+1,-1)
85   end;
86   ans[p[i]]:=find(z[i]);
87  end;
88  for i:=1 to m do
89  writeln(ans[i]);
90 end.