最長非降子序列nlogn C++實現

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

int main()
{
    int n, x;
    vector<int> v, vec;
    cin >> n;
    for (int i = 0; i < n; ++i) {
        cin >> x;
        v.push_back(x);
    }
    for (int i = 0; i < (int)v.size(); ++i) {
        if (i == 0) vec.push_back(v[0]);
        else {
            if (v[i] >= vec[vec.size() - 1]) vec.push_back(v[i]);
            else *upper_bound(vec.begin(), vec.end(), v[i]) = v[i];
        }
    }
    for (int i = 0; i < (int)vec.size(); ++i) {
        cout << vec[i] << ' ';
    }
    cout << endl;
    cout << "len == " << vec.size() << endl;
}

/*
9
2 1 5 3 6 4 8 9 7
*/