[51nod p3111] xiaoming'ai intercepts [Las]

$link$

analysis ：

See the data range $nlogn$ Find the longest non ascending subsequence
It's just $upper\_bound$ Followed by $greater$ You can find the first position less than
Of course Tree array do $nlogn$

CODE：

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#define reg register
using namespace std;
typedef long long ll;
const int N=1e5+5;
int n,a[N],f[N],ans;
int main(){
    
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
		scanf("%d",&a[i]);
	f[++ans]=a[1];
	for(int i=2;i<=n;i++)
	{
    
		if(a[i]<=f[ans]) f[++ans]=a[i];
		else 
		{
    
			int p=upper_bound(f+1,f+ans+1,a[i],greater<int>())-f;
			f[p]=a[i];
		}
	}
	printf("%d",ans);
	return 0;
}