Submission #797818

#	Time	Username	Problem	Language	Result	Execution time	Memory
797818		resting	Meetings (IOI18_meetings)	C++17	0 / 100	40 ms	34856 KiB

meetings

#include "meetings.h"
#include <bits/stdc++.h>
using namespace std;

#define ll long long

int n, q;
struct segtree {
    int l, r, v = 0;
    segtree* lc, * rc;
    segtree* getmem();
    segtree() : segtree(-1, -1) {};
    segtree(int l, int r) : l(l), r(r) {
        if (l == r) return;
        int m = (l + r) / 2;
        lc = getmem(); *lc = segtree(l, m);
        rc = getmem(); *rc = segtree(m + 1, r);
    }
    void upd(int qi, int qv) {
        if (r < qi || l > qi) return;
        if (l == r) { v = qv; return; }
        lc->upd(qi, qv); rc->upd(qi, qv);
        v = max(lc->v, rc->v);
    }
    int q(int ql, int qr) {
        if (l > qr || r < ql) return 0;
        if (ql <= l && r <= qr) return v;
        return max(lc->q(ql, qr), rc->q(ql, qr));
    }
};
segtree mem[1000005];
int memsz = 0;
segtree* segtree::getmem() { return &mem[memsz++]; }

vector<ll> helper(vector<int> h, vector<int> l, vector<int> r) {
    vector<vector<pair<int, int>>> qq(n);
    for (int i = 0; i < q; i++) qq[r[i]].push_back({ l[i], i });
    vector<ll> c(q);
    ll curad = 0;
    set <pair<int, pair<ll, ll>>> s; //position, {const, slope}
    vector<pair<int, pair<ll, int>>> st; // index, {value, height} 
    vector<vector<int>> overtake(n + 1);

    auto find_overtake = [&](pair<ll, ll> a, pair<ll, ll>b) -> int { // when a overtakes b as smallest iykyk
        assert(b.second >= a.second); // or its the other way around
        if (a.first <= b.first && a.second <= b.second) return 0;
        if (b.first >= a.first && b.second >= a.second) return n;
        //first i when b.first + b.second * i > a.first + a.second * i
        // (b.second - a.second) * i > a.first - b.first
        // i > (a.first - b.first) / a.second - b.second
        int div = b.second - a.second;
        return (int)(a.first - b.first + (div - 1)) / div;
    };


    segtree ac(0, n - 1);
    for (int i = 0; i < n; i++) {
        //cout << h[i] << endl;
        ac.upd(i, h[i]);
        while (st.size() && st.back().second.second < h[i]) st.pop_back();
        if (st.size())curad = st.back().second.first + (i - st.back().first) * h[i];
        else curad = (i + 1) * h[i];
        st.push_back({ i, {curad, h[i]} });

        //merge set
        ll mn = curad - h[i] * i;int mni = i;
        while (s.size() && prev(s.end())->second.second <= h[i]) {
            ll t = prev(s.end())->second.first + prev(s.end())->second.second * (i - 1) - h[i] * (i - 1);
            if (t < mn) {
                mn = t; mni = prev(s.end())->first;
            }
            //cout << "erased: " << prev(s.end())->first << endl;
            s.erase(prev(s.end()));
        }
        s.insert({ mni, {mn, h[i]} });
        //cout << "insert: " << mni << "," << mn << "," << h[i] << endl;
        if (s.size() > 1) {
            overtake[max(i, min(n, find_overtake(prev(s.end())->second, prev(prev(s.end()))->second)))].push_back(prev(s.end())->first);
        }
        for (int k = 0; k < overtake[i].size(); k++) {
            auto& x = overtake[i][k];
            auto t = s.lower_bound({ x, {0LL, 0LL} });
            if (t == s.begin() || t == s.end() || t->first != x) continue;
            auto p = prev(t);
            if (p->second.first + p->second.second * i < t->second.first + t->second.second * i) continue;
            //cout << "erased: " << p->first << endl;
            s.erase(p);
            if (t == s.begin()) continue;
            auto pp = prev(t);
            overtake[max(i, min(n, find_overtake(t->second, pp->second)))].push_back(t->first);
        }

        for (auto& x : qq[i]) {
            c[x.second] = 1e18;
            int l = x.first;
            auto owo = lower_bound(st.begin(), st.end(), pair<int, pair<ll, int>>({ l, {0LL, 0} }));
            auto lll = s.lower_bound({ owo->first, {0LL, 0LL} });
            if (lll == s.end()) continue;
            //cout << x.second << " ans " << lll->second.first << " " << lll->second.second << " " << i << " " << owo->second.first << " " << owo->first << " " << owo->second.second << endl;
            c[x.second] = lll->second.first + lll->second.second * i - owo->second.first + (owo->first - l + 1) * owo->second.second;
        }
    }
    //cout << endl;
    return c;
}

vector<ll> minimum_costs(vector<int> h, vector<int> l, vector<int> r) {
    n = h.size(); q = l.size();
    vector<ll> a = helper(h, l, r);
    reverse(h.begin(), h.end()); for (int i = 0; i < q; i++) { swap(l[i], r[i]); l[i] = n - 1 - l[i]; r[i] = n - 1 - r[i]; }
    vector<ll> b = helper(h, l, r);

    vector<ll> c(q); for (int i = 0; i < q;i++) c[i] = min(a[i], b[i]);
    return c;
}

// int32_t main() {
//     vector<ll> c = minimum_costs({ 1, 2, 3, 1, 2, 3, 1, 1, 3, 1 }, { 0 }, { 9 });
//     for (auto& x : c) cout << x << " ";
//     cout << endl;
// }

Compilation message (stderr)

meetings.cpp: In function 'std::vector<long long int> helper(std::vector<int>, std::vector<int>, std::vector<int>)':
meetings.cpp:80:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   80 |         for (int k = 0; k < overtake[i].size(); k++) {
      |                         ~~^~~~~~~~~~~~~~~~~~~~
meetings.cpp:20:23: warning: 'ac.segtree::lc' may be used uninitialized in this function [-Wmaybe-uninitialized]
   20 |         if (r < qi || l > qi) return;
      |                       ^
meetings.cpp:56:13: note: 'ac.segtree::lc' was declared here
   56 |     segtree ac(0, n - 1);
      |             ^~
meetings.cpp:22:9: warning: 'ac.segtree::rc' may be used uninitialized in this function [-Wmaybe-uninitialized]
   22 |         lc->upd(qi, qv); rc->upd(qi, qv);
      |         ^~
meetings.cpp:56:13: note: 'ac.segtree::rc' was declared here
   56 |     segtree ac(0, n - 1);
      |             ^~

• Subtask 1: 0 / 4
• Subtask 2: 0 / 15
• Subtask 3: 0 / 17
• Subtask 4: 0 / 24
• Subtask 5: 0 / 40