24158번: ビルの飾りつけ (Building) ↗

#include <bits/stdc++.h>

#define for1(s,n) for(int i = s; i < n; i++)
#define for1j(s,n) for(int j = s; j < n; j++)
#define foreach(k) for(auto i : k)
#define foreachj(k) for(auto j : k)
#define pb(a) push_back(a)
#define sz(a) a.size()

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef vector <int> iv1;
typedef vector <vector<int> > iv2;
typedef vector <ll> llv1;
typedef unsigned int uint;
typedef vector <ull> ullv1;
typedef vector <vector <ull> > ullv2;

struct LIS {
  llv1 ar;

  llv1 v, buffer;
  llv1::iterator vv;
  vector<pair<ll, ll> > d;

  void perform() {
    v.pb(2000000000ll);

    ll n = sz(ar);

    for1(0, n){
      if (ar[i] > *v.rbegin()) {
        v.pb(ar[i]);
        d.push_back({ v.size() - 1, ar[i] });
      }
      else {
        vv = lower_bound(v.begin(), v.end(), ar[i]);
        *vv = ar[i];
        d.push_back({ vv - v.begin(), ar[i] });
      }
    }

    for(int i = sz(d) - 1; i > -1; i--){
      if(d[i].first == sz(v)-1){
        buffer.pb(d[i].second);
        v.pop_back();
      }
    }

    reverse(buffer.begin(), buffer.end());
  }

  ll getLength() {
    return buffer.size();
  }

  llv1 getLIS() {
    return buffer;
  }
};



int main() {
  ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  ll N, a;
  LIS lis;

  cin >> N;

  while(N--) {
    cin >> a;
    lis.ar.push_back(a);
  }

  lis.perform();

  cout << lis.getLength();
}