【平衡树】【pb_ds】 bzoj1861 [Zjoi2006]Book 书架

需要用数组记录编号为i的书的位置，和位置i处的书的编号。

Code:

 1 #include<cstdio>
 2 #include<ext/pb_ds/assoc_container.hpp>
 3 #include<ext/pb_ds/tree_policy.hpp>
 4 using namespace std;
 5 using namespace __gnu_cxx;
 6 using namespace __gnu_pbds;
 7 tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> T;
 8 typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>::iterator ITER;
 9 //往bzoj上交时，请将null_type改成null_mapped_type
10 int Pos[100001],Val[500001],a,x,n,m;
11 char op[7];
12 int main()
13 {
14     scanf("%d%d",&n,&m);
15     for(int i=1;i<=n;i++)
16       {
17         scanf("%d",&Val[i+100000]);
18         Pos[Val[i+100000]]=i+100000;
19         T.insert(i+100000);
20       }
21     for(int i=1;i<=m;i++)
22       {
23         scanf("%s",op);
24         if(op[0]==‘T‘)
25           {
26             scanf("%d",&a);
27             int tmp=*T.find_by_order(0);
28             T.erase(T.lower_bound(Pos[a]));
29             Pos[a]=tmp-1;
30             Val[tmp-1]=a;
31             T.insert(tmp-1);
32           }
33         else if(op[0]==‘B‘)
34           {
35             scanf("%d",&a);
36             int tmp=*T.find_by_order(n-1);
37             T.erase(T.lower_bound(Pos[a]));
38             Pos[a]=tmp+1;
39             Val[tmp+1]=a;
40             T.insert(tmp+1);
41           }
42         else if(op[0]==‘I‘)
43           {
44             scanf("%d%d",&a,&x);
45             if(x==0)
46               continue;
47             ITER it=T.lower_bound(Pos[a]);
48             ITER it_Beside=it;
49             if(x==1)
50               it_Beside++;
51             else
52               it_Beside--;
53             swap(Val[*it],Val[*it_Beside]);
54             swap(Pos[Val[*it]],Pos[Val[*it_Beside]]);
55           }
56         else if(op[0]==‘A‘)
57           {
58             scanf("%d",&a);
59             printf("%d\n",T.order_of_key(Pos[a]));
60           }
61         else
62           {
63             scanf("%d",&a);
64             printf("%d\n",Val[*T.find_by_order(a-1)]);
65           }
66       }
67     return 0;
68 }