疑问

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cmath>
using namespace std;
const int N = 2e5+10;
int size;
struct qqq{
	int l,r,t,idx;
	bool operator<(qqq& y)
	{
		return l/size==y.l/size?(r/size==y.r/size?t<y.t:r<y.r):l<y.l;
	}
}q[N];
struct ccc{
	int pos,val;
}c[N];
int a[N],b[N],s[N],bl[N];
int cnt1[N],cnt2[N],ans[N];
int l,r,now;		//左右端点指针、时间指针 
int n,m; 

inline int read()
{
	char ch=getchar();bool f=0;int x=0;
	for(;!isdigit(ch);ch=getchar())if(ch=='-')f=1;
	for(;isdigit(ch);ch=getchar())x=(x<<1)+(x<<3)+(ch^48);
	if(f==1)x=-x;return x;
}

void add(int x)
{
	--cnt2[cnt1[x]];
	++cnt2[++cnt1[x]];
}
void del(int x)
{
	--cnt2[cnt1[x]];
	++cnt2[--cnt1[x]];
}

void change(int x,int i)
{
	if(q[i].l<=c[x].pos && c[x].pos<=q[i].r)
	{
		del(a[c[x].pos]) , add(c[x].val);
	}
	swap(c[x].val,a[c[x].pos]);
}

bool cmp(qqq A,qqq B)
{
	return A.l/size==B.l/size?(A.r==B.r?A.t<B.t:A.r<B.r):A.l<B.l;
}

void get_ans(int &x)
{
	for(ans[x]=1; cnt2[ans[x]]>0; ++ans[x]);
}

int main()
{
	n = read() ; m = read();
	size = pow(n,0.67);	//块的大小
	
	for(int i=1; i<=n; i++) 
	{
		a[i]= read() ; s[i] = a[i] ;
	}
	
	int op , qt = 0 , ct = 0 ;
	for(int i=1; i<=m; i++) 
	{
		op= read() ; l= read() ; r = read() ;
		if(op==1)	//询问
			++qt , q[qt].l = l , q[qt].r = r , q[qt].t = ct , q[qt].idx = qt;
		else		//修改 
			++ct , c[ct].pos = l , c[ct].val = r , s[n+ct] = r;
	}
	//离散化的板子
	sort(s+1,s+n+ct+1);
	int sum=unique(s+1,s+n+ct+1)-s-1;
	for(int i=1; i<=n; i++)
		a[i]=lower_bound(s+1,s+sum+1,a[i])-s;
	for(int i=1; i<=ct; i++)
		c[i].val=lower_bound(s+1,s+sum+1,c[i].val)-s;
	
	//询问排序 
	sort(q+1,q+qt+1);
	l = 1 , r = 0 , now = 0;
	for(int i=1; i<=qt; i++)
	{
		int ql = q[i].l , qr = q[i].r , qt = q[i].t;
		while(ql > l)	del(a[l++]);
		while(ql < l)	add(a[--l]);
		while(qr > r)	add(a[++r]);
		while(qr < r)	del(a[r--]);
		while(qt > now)	change(++now,i);
		while(qt < now)	change(now--,i);
		get_ans(q[i].idx);
	}
	
	for(int i=1; i<=qt; i++)
		cout<<ans[i]<<"\n";
	
	return 0;
}
/*
10 3
1 2 3 1 1 2 2 2 9 9
1 2 8
2 7 1
1 2 8

*/