CSES-solutions/CSES Problem Set/Projects.cpp

/* Problem URL: https://cses.fi/problemset/task/1140 */

#include <bits/stdc++.h>

using namespace std;

#define V vector

#define rmin(a, b) a = min(a, b)
#define rmax(a, b) a = max(a, b)

#define rep(i, lim) for (size_t i = 0; i < (lim); i++)
#define nrep(i, s, lim) for (size_t i = s; i < (lim); i++)

#define repv(i, v) for (auto &i : (v))
#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
#define sortv(v) sort(v.begin(), v.end())
#define all(v) (v).begin(), (v).end()

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;

using ll = long long;

using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vvvvl = vector<vvvl>;

template<class v>
auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
    os << vec[0];
    for (size_t i = 1; i < vec.size(); i++) {
        os << ' ' << vec[i];
    }
    os << '\n';
    return os;
}

template<class v>
auto operator>>(istream &is, vector<v> &vec)->istream& {
    for (auto &i : vec) {
        is >> i;
    }
    return is;
}

template<class v>
auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
    for (auto &i : vec) {
        os << i[0];
        for (size_t j = 1; j < i.size(); j++) {
            os << ' ' << i[j];
        }
        os << '\n';
    }
    return os;
}

template<class v>
auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
    for (auto &i : vec) {
        for (auto &j : i) {
            is >> j;
        }
    }
    return is;
}

class segtree {
    vl seg;

    ll _query(int i, int l, int r, int ql, int qr) {
        if (l > qr || r < ql) {
            return -1;
        }

        if (l >= ql && r <= qr) {
            return seg[i];
        }

        int mid = (l + r) / 2;
        return max(_query(i * 2, l, mid, ql, qr), _query(i * 2 + 1, mid + 1, r, ql, qr));
    }

    public:
    segtree() = delete;
    segtree(vl &items): seg(items.size() * 2) {
        size_t n = items.size();
        for (size_t i = n; i < n * 2; i++) {
            seg[i] = items[i - n];
        }

        for (size_t i = n - 1; i > 0; i--) {
            seg[i] = max(seg[i * 2], seg[i * 2 + 1]);
        }
    }

    void update(ll v, int i) {
        i += seg.size() / 2;
        if (seg[i] >= v) {
            return;
        }
        seg[i] = v;
        i /= 2;
        for (; i > 0; i /= 2) {
            seg[i] = max(seg[i * 2], seg[i * 2 + 1]);
        }
    }

    ll query(int i) {
        return _query(1, 0, seg.size() / 2 - 1, 0, i);
    }
};

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;
    V<tuple<ll, ll, ll>> fds(n);
    set<ll> lol;
    for (auto &[i, e, v] : fds) {
        cin >> i >> e >> v;
        lol.insert(e);
    }

    pair<vl, vl> ends(vl(lol.size(), 0), vl(lol.size()));
    auto itr = lol.begin();
    for (size_t i = 0; itr != lol.end(); i++, itr++) {
        ends.second[i] = *itr;
    }

    sort(fds.begin(), fds.end());

    ll neutral = 1e9 + 1;
    while (__builtin_popcount(ends.second.size()) != 1) {
        ends.first.push_back(-1);
        ends.second.push_back(neutral++);
    }

    segtree seg(ends.first);

    for (auto [i, f, v] : fds) {
        auto itr = lower_bound(ends.second.begin(), ends.second.end(), i);
        if (itr == ends.second.begin()) {
            seg.update(v, lower_bound(ends.second.begin(), ends.second.end(), f) - ends.second.begin());
            continue;
        }

        ll up = seg.query(itr - ends.second.begin() - 1) + v;
        seg.update(up, lower_bound(ends.second.begin(), ends.second.end(), f) - ends.second.begin());
    }

    cout << seg.query(ends.first.size() - 1) << '\n';
}