P2617 Dynamic Rankings（主席树+树状数组）

 1 #include"bits/stdc++.h"
 2 using namespace std;
 3 #define nn 40000000
 4 #define lowbit(x) ((x)&(-x))
 5 
 6 int rt[nn],b[nn],a[nn],ca[nn],cb[nn],cc[nn] ;  
 7 int size[nn],xx[nn],yy[nn],l[nn],r[nn];
 8 int n,m;
 9 int totn;
10 int tot,totx,toty;
11 
12 inline int read(){
13     int f=1,x=0;char ch;
14     do{ch=getchar();if(ch==‘-‘)f=-1;}while(ch<‘0‘||ch>‘9‘);
15     do{x=x*10+ch-‘0‘;ch=getchar();}while(ch>=‘0‘&&ch<=‘9‘);
16     return f*x;
17 }
18 
19 
20 void change(int &y,int x,int L,int R,int pos,int v)
21 {
22       y=++tot; size[tot]=size[x]+v,l[tot]=l[x],r[tot]=r[x];
23     if (L==R)return ;
24     int mid = R+L>>1;if (pos<=mid)change(l[tot],l[x],L,mid,pos,v);
25     else change(r[tot],r[x],mid+1,R,pos,v);
26 }
27 
28 inline void add(int x,int v)
29 {
30     int k = lower_bound(b+1,b+1+totn,a[x])-b;
31     for (int i=x;i<=n;i+=lowbit(i)) change(rt[i],rt[i],1,totn,k,v);
32 }
33 
34 int query(int L,int R,int p)
35 {
36     if (L==R)return R; int sum=0; int mid = L+R>>1;
37     for (int i=1;i<=totx;i++)sum-=size[l[xx[i]]];
38     for (int i=1;i<=toty;i++)sum+=size[l[yy[i]]];
39     if (p<=sum)
40     {
41        for ( int i=1;i<=totx;i++)xx[i]=l[xx[i]];
42        for ( int i=1;i<=toty;i++)yy[i]=l[yy[i]];
43        return query(L,mid,p);
44     }
45      for ( int i=1;i<=totx;i++)xx[i]=r[xx[i]];
46        for ( int i=1;i<=toty;i++)yy[i]=r[yy[i]];
47       return query(mid+1,R,p-sum);
48 }
49 
50 int main()
51 {  char s;
52     n=read(),m=read();
53     for (int i=1;i<=n;i++)a[i]=read(),b[++totn]=a[i];
54 
55     for (int i=1;i<=m;i++) 
56     {
57         cin>>s; if (s==‘Q‘) ca[i]=read(),cb[i]=read(),cc[i]=read();
58         else ca[i]=read(),cb[i]=read(),b[++totn]=cb[i];
59     }
60         sort(b+1,b+1+totn);
61     totn=unique(b+1,b+1+totn)-b-1;
62     
63     for ( int i=1;i<=n;i++) add(i,1); 
64     for ( int i=1;i<=m;i++)
65     {
66         if (cc[i]) 
67         {  totx=toty=0;
68             for ( int j=ca[i]-1;j;j-=lowbit(j))xx[++totx]=rt[j];
69             for ( int j=cb[i];j;j-=lowbit(j))yy[++toty]=rt[j];
70             printf("%d\n",b[query(1,totn,cc[i])]);
71         }
72         else 
73         {
74             add(ca[i],-1),a[ca[i]]=cb[i],add(ca[i],1);
75         }
76     }
77     
78 }