思路

C++ 代码

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

const int N = 100010;

int  n  , a[N] ;
vector<int> v;

int main()
{ 
    cin >> n ;
    for(int i = 0 ; i < n ; i++ )   cin >> a[i] ;

    int len = 0 ;
    for(int i = 0 ; i < n ; i++ ){
        auto it = lower_bound(v.begin(),v.end(),a[i]);
        if(it == v.end())   v.push_back(a[i]);
        else    *it = a[i];
    }

    cout << v.size() << endl;
    return 0;
}