ZOJ 2112 Dynamic Rankings （动态第k大，树状数组套主席树）★★

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std;

const int MAXN = 60010;
const int M = 2500010;
int n,q,m,tot;
int a[MAXN], t[MAXN];
int T[MAXN], lson[M], rson[M],c[M];
int S[MAXN];

struct Query
{
int kind;
int l,r,k;
}query[10010];

void Init_hash(int k)
{
sort(t,t+k);
m = unique(t,t+k) - t;
}
int hash(int x)
{
return lower_bound(t,t+m,x)-t;
}
int build(int l,int r)
{
int root = tot++;
c[root] = 0;
if(l != r)
{
int mid = (l+r)/2;
lson[root] = build(l,mid);
rson[root] = build(mid+1,r);
}
return root;
}

int Insert(int root,int pos,int val)
{
int newroot = tot++, tmp = newroot;
int l = 0, r = m-1;
c[newroot] = c[root] + val;
while(l < r)
{
int mid = (l+r)>>1;
if(pos <= mid)
{
lson[newroot] = tot++; rson[newroot] = rson[root];
newroot = lson[newroot]; root = lson[root];
r = mid;
}
else
{
rson[newroot] = tot++; lson[newroot] = lson[root];
newroot = rson[newroot]; root = rson[root];
l = mid+1;
}
c[newroot] = c[root] + val;
}
return tmp;
}

int lowbit(int x)
{
return x&(-x);
}
int use[MAXN];
void add(int x,int pos,int val)
{
while(x <= n)
{
S[x] = Insert(S[x],pos,val);
x += lowbit(x);
}
}
int sum(int x)
{
int ret = 0;
while(x > 0)
{
ret += c[lson[use[x]]];
x -= lowbit(x);
}
return ret;
}
int Query(int left,int right,int k)
{
int left_root = T[left-1];
int right_root = T[right];
int l = 0, r = m-1;
for(int i = left-1;i;i -= lowbit(i)) use[i] = S[i];
for(int i = right;i ;i -= lowbit(i)) use[i] = S[i];
while(l < r)
{
int mid = (l+r)/2;
int tmp = sum(right) - sum(left-1) + c[lson[right_root]] - c[lson[left_root]];
if(tmp >= k)
{
r = mid;
for(int i = left-1; i ;i -= lowbit(i))
use[i] = lson[use[i]];
for(int i = right; i; i -= lowbit(i))
use[i] = lson[use[i]];
left_root = lson[left_root];
right_root = lson[right_root];
}
else
{
l = mid+1;
k -= tmp;
for(int i = left-1; i;i -= lowbit(i))
use[i] = rson[use[i]];
for(int i = right;i ;i -= lowbit(i))
use[i] = rson[use[i]];
left_root = rson[left_root];
right_root = rson[right_root];
}
}
return l;
}
void Modify(int x,int p,int d)
{
while(x <= n)
{
S[x] = Insert(S[x],p,d);
x += lowbit(x);
}
}

int main()
{
//freopen("in.txt","r",stdin);
//freopen("out.txt","w",stdout);
int Tcase;
scanf("%d",&Tcase);
while(Tcase--)
{
scanf("%d%d",&n,&q);
tot = 0;
m = 0;
for(int i = 1;i <= n;i++)
{
scanf("%d",&a[i]);
t[m++] = a[i];
}
char op[10];
for(int i = 0;i < q;i++)
{
scanf("%s",op);
if(op[0] == 'Q')
{
query[i].kind = 0;
scanf("%d%d%d",&query[i].l,&query[i].r,&query[i].k);
}
else
{
query[i].kind = 1;
scanf("%d%d",&query[i].l,&query[i].r);
t[m++] = query[i].r;
}
}
Init_hash(m);
T[0] = build(0,m-1);
for(int i = 1;i <= n;i++)
T[i] = Insert(T[i-1],hash(a[i]),1);
for(int i = 1;i <= n;i++)
S[i] = T[0];
for(int i = 0;i < q;i++)
{
if(query[i].kind == 0)
printf("%d\n",t[Query(query[i].l,query[i].r,query[i].k)]);
else
{
Modify(query[i].l,hash(a[query[i].l]),-1);
Modify(query[i].l,hash(query[i].r),1);
a[query[i].l] = query[i].r;
}
}
}
return 0;
}