这个题在kuangbin大佬的模板里有。
http://www.cnblogs.com/kuangbin/p/3308118.html
kuangbin大佬博客里有四个学习连接。
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 60010;
struct node
{
int l,r,sum;
}T[MAXN*30];
int root[MAXN],a[MAXN];
int S[MAXN],use[MAXN];
vector<int> vec;
int n,m,cnt,siz;
struct Query
{
char op;
int l,r,k;
}qs[10010];
int getid(int x)
{
return lower_bound(vec.begin(), vec.end(), x) - vec.begin() + 1;
}
void update(int l, int r, int &x, int y, int pos, int val)
{
T[++cnt] = T[y];
T[cnt].sum += val;
x = cnt;
if(l == r) return;
int mid = (l+r)>>1;
if(pos <= mid) update(l, mid, T[x].l, T[y].l, pos, val);
else update(mid+1, r, T[x].r, T[y].r, pos, val);
}
#define lowbit(x) (x&(-x))
void Modify(int x, int pos, int val)
{
while(x <= n)
{
update(1, siz, S[x], S[x], pos, val);
x += lowbit(x);
}
}
int Sum(int x)
{
int ret = 0;
while(x)
{
ret += T[T[use[x]].l].sum;
x -= lowbit(x);
}
return ret;
}
int query(int l, int r, int u, int v, int x, int y, int k)
{
if(l >= r) return l;
int mid = (l+r) >> 1;
int tmp = Sum(v)-Sum(u) + T[T[y].l].sum - T[T[x].l].sum;
if(tmp >= k)
{
for(int i = u; i; i -= lowbit(i)) use[i] = T[use[i]].l;
for(int i = v; i; i -= lowbit(i)) use[i] = T[use[i]].l;
return query(l,mid,u,v,T[x].l,T[y].l,k);
}
else
{
for(int i = u; i; i -= lowbit(i)) use[i] = T[use[i]].r;
for(int i = v; i; i -= lowbit(i)) use[i] = T[use[i]].r;
return query(mid+1,r,u,v,T[x].r,T[y].r,k-tmp);
}
}
int ask(int l, int r, int k)
{
for(int i = l-1; i; i -= lowbit(i))
use[i] = S[i];
for(int i = r; i; i -= lowbit(i))
use[i] = S[i];
int ret = query(1,siz,l-1,r,root[l-1],root[r],k)-1;
return vec[ret];
}
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
cnt = 0;
vec.clear();
T[0].l = T[0].r = T[0].sum = 0;
scanf("%d %d",&n,&m);
for(int i = 1; i <= n; ++i)
{
scanf("%d",&a[i]);
vec.push_back(a[i]);
}
for(int i = 0; i < m; ++i)
{
scanf(" %c",&qs[i].op);
if(qs[i].op == 'Q')
scanf("%d %d %d",&qs[i].l,&qs[i].r,&qs[i].k);
else
{
scanf("%d %d",&qs[i].l,&qs[i].r);
vec.push_back(qs[i].r);
}
}
sort(vec.begin(),vec.end());
vec.erase(unique(vec.begin(),vec.end()), vec.end());
siz = vec.size();
for(int i = 1; i <= n; ++i)
update(1,siz,root[i],root[i-1],getid(a[i]),1);
memset(S,0,sizeof(S));
for(int i = 0; i < m; ++i)
{
if(qs[i].op == 'Q')
printf("%d\n",ask(qs[i].l, qs[i].r, qs[i].k));
else
{
Modify(qs[i].l, getid(a[qs[i].l]), -1);
Modify(qs[i].l, getid(qs[i].r), 1);
a[qs[i].l] = qs[i].r;
}
}
}
return 0;
}