bzoj 2743 树状数组离线查询

我们按照询问的右端点排序，然后对于每一个位置，记录同颜色

上一个出现的位置，每次将上上位置出现的+1，上次出现的-1，然后

用树状数组维护就好了

 

/**************************************************************
    Problem: 2743
    User: BLADEVIL
    Language: Pascal
    Result: Accepted
    Time:11072 ms
    Memory:70540 kb
****************************************************************/
 
//By BLADEVIL
var
    n, m, t, l                      :longint;
    pre, other, num                 :array[0..2000005] of longint;
    last, ans, first, a, pred, c    :array[0..2000005] of longint;
     
procedure connect(x,y,tot:longint);
begin
    inc(l);
    pre[l]:=last[x];
    last[x]:=l;
    other[l]:=y;
    num[l]:=tot;
end;
  
procedure add(x,y:longint);
begin
    while (x<=n) do
    begin
        inc(c[x],y);
        x:=x+(x and -x);
    end;
end;
  
function ask(x:longint):longint;
var    
    sum                             :longint;
begin
    sum:=0;
    while x>0 do
    begin
        sum:=sum+c[x];
        x:=x-(x and -x);
    end;
    exit(sum);
end;
 
procedure init;
var
    i, j                            :longint;
    x, y                            :longint;
     
begin
    readln(n,t,m);
    for i:=1 to n do
    begin
        read(a[i]);
        if first[a[i]]<>0 then pred[i]:=first[a[i]];
        first[a[i]]:=i;
    end;
     
    for i:=1 to m do
    begin
        readln(x,y);
        connect(y,x,i);
    end;
end;
 
procedure main;
var
    i                               :longint;
    q, p                            :longint;
     
begin
    for i:=1 to n do
    begin
        add(pred[pred[i]]+1,1);
        add(pred[i]+1,-1);
        q:=last[i];
        while q<>0 do
        begin
            p:=other[q];
            ans[num[q]]:=ask(p);
            q:=pre[q];
        end;
    end;
    for i:=1 to m do writeln(ans[i]);
end;
  
begin
    init;
    main;
end.