Submission #668794

#	Time	Username	Problem	Language	Result	Execution time	Memory
668794		vuavisao	Lasers (NOI19_lasers)	C++14	87 / 100	120 ms	31832 KiB

lasers

#include<bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#define ll long long
using namespace std;

template<typename Lhs, typename Rhs> inline void Max_self(Lhs &a, Rhs b) { a = (a > b ? a : b); }
template<typename Lhs, typename Rhs> inline void Min_self(Lhs &a, Rhs b) { a = (a < b ? a : b); }

const int N = 5e5 + 10;

int LEN, n;
vector<vector<int>> door;

namespace sub1_2 {
    bool check() {
        for(int i = 0; i < n; ++ i) if(door[i].size() != 1) return false;
        return true;
    }

    void solve() {
        int best = 0;
        for(int i = 0; i < n; ++ i) {
            Max_self(best, door[i][0]);
        }
        int res = 2 * max(0, best - (LEN / 2));
        if(res > 0) res -= (LEN & 1);
        cout << res;
    }
}

namespace sub3_4 {
    bool check() {
        bool check_sub = false;
        if(LEN <= 1000000 && n == 2) check_sub = true;
        int cnt_door = 0;
        for(int i = 0; i < n; ++ i) cnt_door += door[i].size();
        if(LEN <= 1000 && cnt_door <= 1000) check_sub = true;
        return check_sub;
    }

    vector<vector<int>> pred;

    int sum_to(int l, int r, int idx) {
        if(l > r) return 0;
        if(l == 0) return pred[idx][r];
        return pred[idx][r] - pred[idx][l - 1];
    }

    bool calc_line(int idx) {
        for(int i = 0; i < n; ++ i) {
            const auto& psy = pred[i];
            int first = lower_bound(psy.begin(), psy.end(), idx) - psy.begin();
            int len_last = sum_to(first, psy.size() - 1, i);
            if(LEN - len_last + 1 <= idx) return false;
        }
        return true;
    }

    void solve() {
        for(int i = 0; i < n; ++ i) {
            auto psy = door[i];
            vector<int> tmp(psy.size());
            for(int j = 0; j < psy.size(); ++ j) {
                if(j == 0) tmp[j] = psy[j];
                else tmp[j] = tmp[j - 1] + psy[j];
            }
            pred.push_back(tmp);
        }
        int res = 0;
        for(int i = 1; i <= LEN; ++ i) res += calc_line(i);
        cout << LEN - res;
    }
}

namespace sub5 {
    bool check() {
        return LEN <= 1000000;
    }

    struct state {
        int v = 0, w = 0, last = 0, idx = 0;
        state() {};
        state(int _v, int _w, int _last, int _idx) { v = _v; w = _w; last = _last; idx = _idx; };

        bool operator < (const state& other) const {
            return this -> w < other.w;
        }
    };

    vector<int> pred;

    void solve() {
        vector<state> buffer = {};
        multiset<int, greater<int>> mst = {};
        for(int i = 0; i < n; ++ i) {
            auto psy = door[i];
            vector<int> tmp(psy.size());
            for(int j = 0; j < psy.size(); ++ j) {
                if(j == 0) tmp[j] = psy[j];
                else tmp[j] = tmp[j - 1] + psy[j];
                buffer.push_back(state(j, tmp[j], (j == 0 ? 0 : tmp[j - 1]), i));
            }
            mst.insert(tmp.back());
            pred.push_back(tmp.back());
        }
        sort(buffer.begin(), buffer.end());
        int res = 0;
        for(int i = 1, j = 0; i <= LEN; ++ i) {
            while(j < buffer.size() && buffer[j].w < i) {
                auto psy = buffer[j];
                auto tmp = mst.find(pred[psy.idx] - psy.last);
                if(tmp != mst.end()) mst.erase(tmp);
                else assert(false);
                mst.insert(pred[psy.idx] - psy.w);
                ++ j;
            }
            int first_right = LEN - *mst.begin() + 1;
            if(first_right > i) res++;
        }
        cout << LEN - res;
    }
}

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if (fopen("lasers.inp", "r")) {
        freopen("lasers.inp", "r", stdin);
        freopen("lasers.out", "w", stdout);
    }
    cin >> LEN >> n;
    for(int i = 1; i <= n; ++ i) {
        int cnt; cin >> cnt;
        vector<int> tmp(cnt);
        for(int j = 0; j < cnt; ++ j) cin >> tmp[j];
        door.push_back(tmp);
    }
    if(sub1_2::check()) {
        sub1_2::solve();
        return 0;
    }
    if(sub3_4::check()) {
        sub3_4::solve();
        return 0;
    }
    if(sub5::check()) {
        sub5::solve();
        return 0;
    }
    assert(false);
    return 0;
}

/// Code by vuavisao

Compilation message (stderr)

lasers.cpp: In function 'void sub3_4::solve()':
lasers.cpp:64:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   64 |             for(int j = 0; j < psy.size(); ++ j) {
      |                            ~~^~~~~~~~~~~~
lasers.cpp: In function 'void sub5::solve()':
lasers.cpp:99:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   99 |             for(int j = 0; j < psy.size(); ++ j) {
      |                            ~~^~~~~~~~~~~~
lasers.cpp:110:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<sub5::state>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  110 |             while(j < buffer.size() && buffer[j].w < i) {
      |                   ~~^~~~~~~~~~~~~~~
lasers.cpp: In function 'int32_t main()':
lasers.cpp:130:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  130 |         freopen("lasers.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
lasers.cpp:131:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  131 |         freopen("lasers.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 14 / 14
• Subtask 3: 20 / 20
• Subtask 4: 21 / 21
• Subtask 5: 22 / 22
• Subtask 6: 0 / 13