主席树套树状数组 动态区间第k小

先打上代码以后更新解释

 1 #include <cstdio>
 2 #include <iostream>
 3 #include <algorithm>
 4 #include <cstring>
 5 #include <cmath>
 6 #define REP(i, s, n) for(int i = s; i <= n; i ++)
 7 #define RAP(i, n, s) for(int i = n; i >= s; i --)
 8 #define LOW for(; x; x -= x & (-x))
 9 using namespace std;
10 const int maxn = 100000 + 10;
11 const int Maxn = 100000;
12 const int maxnode = 200 * maxn;
13 int s[maxnode], ls[maxnode], rs[maxnode], A[maxn], root[maxn], Ln, Rn, L[maxn], R[maxn], c[maxn];
14 int n, Q, ms = 0;
15 void update(int x, int& y, int L, int R, int pos, int v){
16     s[y = ++ ms] = s[x] + v;
17     if(L == R) return ;
18     int M = L + R >> 1;
19     ls[y] = ls[x]; rs[y] = rs[x];
20     if(pos <= M) update(ls[x], ls[y], L, M, pos, v);
21     else update(rs[x], rs[y], M + 1, R, pos, v);
22     return ;
23 }
24 void update(int x, int v){
25     for(int i = x; i <= Maxn; i += i & (-i)) update(c[i], c[i], 1, Maxn, A[x], -1); A[x] = v;
26     for(int i = x; i <= Maxn; i += i & (-i)) update(c[i], c[i], 1, Maxn, A[x], 1); return ;
27 }
28 void init(int x, int tp){
29     if(!tp) { L[++ Ln] = root[x]; LOW if(c[x]) L[++ Ln] = c[x]; }
30     else { R[++ Rn] = root[x]; LOW if(c[x]) R[++ Rn] = c[x]; }
31     return ;
32 }
33 int query(int ql, int qr, int k){
34     Ln = Rn = 0; init(qr, 1); init(ql - 1, 0);//0是左
35     int ll = 1, rr = Maxn;
36     while(ll < rr){
37         int Lsum = 0, Rsum = 0, M = ll + rr >> 1;
38         REP(i, 1, Ln) Lsum += s[ls[L[i]]];
39         REP(i, 1, Rn) Rsum += s[ls[R[i]]];
40         int kth = Rsum - Lsum;
41         if(kth >= k){//往左找 
42             REP(i, 1, Ln) L[i] = ls[L[i]];
43             REP(i, 1, Rn) R[i] = ls[R[i]];
44             rr = M;
45         }
46         else{//往右找 
47             REP(i, 1, Ln) L[i] = rs[L[i]];
48             REP(i, 1, Rn) R[i] = rs[R[i]];
49             ll = M + 1; k -= kth; //看好了二分！ 别忘了还要减 Σ( ° △ °|||)︴ 
50         }
51     }
52     return ll;
53 }
54 inline void read(int &x){
55     x = 0; int sig = 1; char ch = getchar();
56     while(!isdigit(ch)) { if(ch == '-') sig = -1; ch = getchar(); }
57     while(isdigit(ch)) x = 10 * x + ch - '0', ch = getchar();
58     x *= sig; return ;
59 }
60 inline void write(int x){
61     if(x == 0) { putchar('0'); return ; }
62     if(x < 0) putchar('-'), x = -x;
63     int len = 0, buf[20];
64     while(x) buf[len ++] = x % 10, x /= 10;
65     RAP(i, len - 1, 0) putchar(buf[i] + '0'); return ;
66 }
67 void init(){
68     read(n); read(Q);
69     REP(i, 1, n) read(A[i]);
70     REP(i, 1, n) update(root[i - 1], root[i], 1, Maxn, A[i], 1);
71     return ;
72 }
73 void work(){
74     int tp, ql, qr, k, x, v;
75     while(Q --){
76         read(tp);
77         if(tp) read(ql), read(qr), read(k), write(query(ql, qr, k) - 1), putchar('\n');// 减一 
78         else read(x), read(v), update(x, v);
79     }
80     return ;
81 }
82 void print(){
83 
84     return ;
85 }
86 int main(){
87     init();
88     work();
89     print();
90     return 0;
91 }

 逗比版：

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<algorithm>
 5 #define t node[d]
 6 #define cnt countn[d]
 7 #define repnode(d) for(int i=1;i<=countn[d];i++)
 8 using namespace std;
 9 const int maxn=100000+10,maxnode=20000000+10,Max=100000;
10 int ls[maxnode],rs[maxnode],s[maxnode],root[maxn],A[maxn],c[maxn],n,m,ms=0,countn[2],node[2][maxn],sum[2];
11 void update(int x,int& y,int L,int R,int pos,int d){
12     s[y=++ms]=s[x]+d;
13     if(L==R) return;
14     ls[y]=ls[x];rs[y]=rs[x];
15     int M=L+R>>1;
16     if(pos<=M) update(ls[x],ls[y],L,M,pos,d);
17     else update(rs[x],rs[y],M+1,R,pos,d);
18     return;
19 }
20 void update(int x,int v){
21     for(int i=x;i<=Max;i+=i&-i) update(c[i],c[i],1,Max,A[x],-1);A[x]=v;
22     for(int i=x;i<=Max;i+=i&-i) update(c[i],c[i],1,Max,A[x],1);return;
23 }
24 void init(int x,int d){
25     t[++cnt]=root[x];
26     for(;x;x-=x&-x) if(c[x]) t[++cnt]=c[x];
27     return;
28 }
29 int query(int ql,int qr,int k){
30     countn[0]=countn[1]=0;
31     init(qr,1);init(ql-1,0);
32     int L=1,R=Max,d;
33     while(L<R){
34         sum[0]=sum[1]=0;
35         int M=L+R>>1;
36         repnode(d=0) sum[d]+=s[ls[t[i]]];
37         repnode(d=1) sum[d]+=s[ls[t[i]]];
38         int kth=sum[1]-sum[0];
39         if(k<=kth){
40             repnode(d=0) t[i]=ls[t[i]];
41             repnode(d=1) t[i]=ls[t[i]];
42             R=M;
43         }
44         else{
45             repnode(d=0) t[i]=rs[t[i]];
46             repnode(d=1) t[i]=rs[t[i]];
47             L=M+1;k-=kth;
48         }
49     } return L;
50 }
51 inline int read(){
52     int x=0,sig=1;char ch=getchar();
53     while(!isdigit(ch)){if(ch=='-') sig=-1;ch=getchar();}
54     while(isdigit(ch)) x=10*x+ch-'0',ch=getchar();
55     return x*=sig;
56 }
57 inline void write(int x){
58     if(x==0){putchar('0');return;} if(x<0) putchar('-'),x=-x;
59     int len=0,buf[15]; while(x) buf[len++]=x%10,x/=10;
60     for(int i=len-1;i>=0;i--) putchar(buf[i]+'0');return;
61 }
62 void init(){
63     n=read();m=read();
64     for(int i=1;i<=n;i++) A[i]=read();
65     for(int i=1;i<=n;i++) update(root[i-1],root[i],1,Max,A[i],1);
66     return;
67 }
68 void work(){
69     int tp,i,j,k,x,v;
70     while(m--){
71         tp=read();
72         if(tp){
73             i=read();j=read();k=read();
74             write(query(i,j,k)-1);putchar('\n');
75         }
76         else{
77             x=read();v=read();
78             update(x,v);
79         }
80     }
81     return;
82 }
83 void print(){
84     return;
85 }
86 int main(){
87     init();work();print();return 0;
88 }