#include<bits/stdc++.h>
using namespace std;
const int maxn=100000,maxt=maxn<<1,maxl=18,maxb=9,maxc=maxt/maxb;
struct node{
	int val;
	int dep,dfn,end;
	node *son[2];
}T[maxn];
int n,t,b,c,Log2[maxc+1];
int Pos[(1<<(maxb-1))+5],Dif[maxc+1];
node *root,*A[maxt],*Min[maxl][maxc];
void build(){
	static node *S[maxn+1];
	int top=0;
	for(int i=0;i<n;i++){
		node *p=&T[i];
		while(top&&S[top]->val<p->val)p->son[0]=S[top];
		if(top)p->son[1]=S[top];
		S[++top]=p;
	}
	root=S[1];
} 
void DFS(node *p){
	A[p->dfn=t++]=p;
	for(int i=0;i<2;i++)
		if(p->son[i]){
			p->son[i]->dep=p->dep+1;
			DFS(p->son[i]);
			A[t++]=p;
		}
	p->end=t-1;
}
node *min(node *x,node *y){
	return x->dep<y->dep?x:y;
}
void ST_init(){
	b=(int)(ceil(log2(t)/2));
	c=t/b;
	Log2[1]=0;
	for(int i=2;i<=c;i++)Log2[i]=Log2[i>>1]+1;
	for(int i=0;i<c;i++){
		Min[0][i]=A[i*b];
		for(int j=1;j<b;j++)Min[0][i]=min(Min[0][i],A[i*b+j]);
	}
	for(int i=1,l=2;l<=c;i++,l<<=1)
		for(int j=0;j+l<=c;j++)Min[i][j]=min(Min[i-1][j],Min[i-1][j+(l>>1)]);
}
void small_init(){
	for(int i=0;i<c;i++)
		for(int j=1;j<b&&i*b+j<t;j++)
			if(A[i*b+j]->dep<A[i*b+j-1]->dep)Dif[i]|=1<<(j-1);
	for(int S=0;S<(1<<(b-1));S++){
		int mx=0,v=0;
		for(int i=1;i<b;i++){
			v+=(S>>(i-1)&1)?-1:1;
			if(v<mx){
				mx=v;
				Pos[S]=i;
			}
		}
	}
}
node *ST_query(int l,int r){
	int g=Log2[r-l+1];
	return min(Min[g][l],Min[g][r-(1<<g)+1]);
}
node *small_query(int l,int r){
	int p=l/b;
	int S=(Dif[p]>>(l-p*b))&((1<<(r-1))-1);
	return A[l+Pos[S]];
}
node *query(int l,int r){
	if(l>r)return query(r,l);
	int pl=l/b,pr=r/b;
	if(pl==pr)return small_query(l,r);
	else{
		node *s=min(small_query(l,pl*b+b-1),small_query(pr*b,r));
		if(pl+1<=pr-1)s=min(s,ST_query(pl+1,pr-1));
		return s;
	}
}
int main(){
	int m;
	cin>>n>>m;
	for(int i=0;i<n;i++)cin>>T[i].val;
	build();
	DFS(root);
	ST_init();
	small_init();
	while(m--){
		int l,r;
		cin>>l>>r;
		cout<<query(T[l].dfn,T[r].dfn)->val<<endl;
	}
	return 0;
}

#include<bits/stdc++.h>
#define N 100010
using namespace std;
int n,a[N];
struct tree{
	int l,r;
	int sum;
	int add;
}t[N<<2];
void pushup(int p){
	t[p].sum=t[p<<1].sum+t[p<<1|1].sum;
}
void pushdown(int p){
    auto &root=t[p],&left=t[p<<1],&right=t[p<<1|1];
    if(root.add){                   
        left.add+=root.add;                         
        left.sum+=(left.r-left.l+1)*root.add; 
        right.add+=root.add;
        right.sum+=(right.r-right.l+1)*root.add;
        root.add=0;
    }
}
void build(int p,int l,int r){
	t[p].l=l,t[p].r=r;
	if(l==r){
		t[p].sum=a[l];
		return;
	}
	int mid=l+r>>1;
	build(p<<1,l,mid);
	build(p<<1|1,mid+1,r);
	pushup(p);
}
void modify(int p,int l,int r,int d){
    if(l<=t[p].l&&t[p].r<=r){  
        t[p].sum+=(t[p].r-t[p].l+1)*d;
        t[p].add+=d; 
        return;    
    }
    pushdown(p);
    int mid=t[p].l+t[p].r>>1;
    if(l<=mid)modify(p<<1,l,r,d);
    if(r>mid)modify(p<<1|1,l,r,d);
    pushup(p); 
}
int query(int p,int l,int r){
    if(l<=t[p].l&&t[p].r<<r)return t[p].sum;
    pushdown(p);
    int mid=t[p].l+t[p].r>>1;
    int sum=0;
    if(l<=mid)sum+=query(p<<1,l,r);
    if(r>mid)sum+=query(p<<1|1,l,r);
    return sum;
}
int main(){
	cin>>n;
	for(int i=1;i<=n;i++)cin>>a[i];
	int x,v,l,r;
	build(1,1,n);
	modify(1,x,v,1);
	query(1,l,r);
	return 0;
}

n=int(input())
a=list(map(int,input().split()))
st=[0]*n
top=-1
cur=1
flag=True
for i in range(n):
    while a[i]>=cur:
        top+=1
        st[top]=cur
        cur+=1
    if st[top]==a[i]:
        top-=1
    else:
        flag=False
        print("NO")
        break
if flag and i==n-1 and top==-1:
    print("YES")

#include<bits/stdc++.h>
using namespace std;
const int maxn=105;
unsigned ack(unsigned m,unsigned n){
    if(m==0)return n+1;
    if(n==0)return ack(m-1,1);
    return ack(m-1,ack(m,n-1));
}
int main(){
    unsigned m,n;
    cin>>m>>n;
    cout<<ack(m,n)<<endl;
    return 0;
}

http://10.209.85.202/noi/2023chusai/08_2020CSP-S/2020级提高级试题.pdf