Submission #494501

#TimeUsernameProblemLanguageResultExecution timeMemory
494501blueMeetings (IOI18_meetings)C++17
60 / 100
5620 ms786432 KiB
#include "meetings.h"
#include <vector>
#include <algorithm>
#include <iostream>
#include <deque>
#include <cassert>
using namespace std;

using ll = long long;
using vll = vector<ll>;
using vi = vector<int>;
using pii = pair<int, int>;
#define sz(x) (int(x.size()))

const int mx = 750'000;
const ll INF = 1'000'000'000'000'000'000LL;


int N;
int Q;

vi H;

vi L, R;
vi M(mx);
vi peak_queries[mx];

vi HD;

vi lc, rc;
vi le, re;
vll ans;








const int e20 = (1<<20);

struct segtree
{
    // int l;
    // int r;
    vector<pii> v = vector<pii>(2*e20, {-1, -1});
    // pii v[2*e20];

    // segtree* left = NULL;
    // segtree* right = NULL;


    segtree()
    {
        ;
    }

    void build_segtree(int L, int R, vi& Z)
    {
        // cerr << "build segtree " << L << ' ' << R << '\n';
        for(int i = L; i <= R; i++)
            v[e20+i] = {Z[i], i};
        for(int i = e20-1; i >= 1; i--)
            v[i] = max(v[2*i], v[2*i+1]);
        // cerr << "build done\n";
    }

    pii rangemax(int L, int R)
    {
        // cerr << "range max called\n";
        // cerr << L << ' ' << R << '\n';
        L = e20+L;
        R = e20+R+1;

        pii res{-1, -1};

        // pii lft_mx{-1, -1}, rgt_mx{-1, -1};
        while(L < R)
        {
            if(L % 2 == 1)
            {
                res = max(res, v[L]);
                L++;
            }
            if(R % 2 == 1)
            {
                R--;
                res = max(res, v[R]);
            }
            L/=2;
            R/=2;
            // cerr << "!\n";
        }

        // cerr << "returning\n";
        return res;
    }
};

segtree ST;

vi subtree;

int build_tree(int l, int r)
{
    if(r < l) return -1;
    // cerr << "build tree " << l << ' ' << r << '\n';
    // cerr << "build tree\n";
    int m = ST.rangemax(l, r).second;
    // cerr << "m = " << m << '\n';
    // cerr << "m = " << m << '\n';
    // cerr << lc[m] << ' ' << rc[m] << '\n';
    lc[m] = build_tree(l, m-1);
    rc[m] = build_tree(m+1, r);

    if(lc[m] != -1) subtree[m] += subtree[lc[m]];
    if(rc[m] != -1) subtree[m] += subtree[rc[m]];

    // cerr << "build tree " << l << ' ' << r << " done\n";

    return m;
}
vector<int> x1, x2;
vector<ll> y1, y2;


// struct seg
// {
//     int i;
// };

int seg_ct = -1;

int new_segment(int X1, ll Y1, int X2, ll Y2)
{
    seg_ct++;
    x1.push_back(X1);
    y1.push_back(Y1);
    x2.push_back(X2);
    y2.push_back(Y2);
    // x1[seg_ct] = X1;
    // y1[seg_ct] = Y1;
    // x2[seg_ct] = X2;
    // y2[seg_ct] = Y2;
    return seg_ct;
}

ll get_slope(int i)
{
    if(x2[i] == x1[i]) return 0;
    else return (y2[i]-y1[i])/(x2[i]-x1[i]);
}

struct func
{
    ll lp = 0;
    deque<int> d;

    void inc(ll W)
    {
        lp += W;
    }

    void push_back(func& K)
    {
        for(int k: K.d)
        {
            y1[k] += K.lp - lp;
            y2[k] += K.lp - lp;
            d.push_back(k);
            // d.push_back(seg{k.x1, k.y1 + K.lp - lp, k.x2, k.y2 + K.lp - lp});
        }
    }

    void push_front(func& K)
    {
        while(!K.d.empty())
        {
            int k = K.d.back();
            y1[k] += K.lp - lp;
            y2[k] += K.lp - lp;
            d.push_front(k);
            K.d.pop_back();
        }
    }

    void front_AP(ll a, ll sl)
    {
        int xf = x1[d.front()];
        int xb = -1;
        while(!d.empty())
        {
            ll dy2 = y2[d.front()] + lp;
            int dx2 = x2[d.front()];

            ll dy1 = y1[d.front()] + lp;
            int dx1 = x1[d.front()];


            ll new_y2 = a + sl*(dx2 - xf);
            if(new_y2 > dy2) break;
            else if(a > dy1) break;
            else
            {
                xb = max(xb, x2[d.front()]);
                d.pop_front();
            }
        }


        if(!d.empty())
        {
            // cerr << "case X\n";
            ll dy1 = y1[d.front()] + lp;
            ll dx1 = x1[d.front()];


            ll new_y1 = a + sl*(dx1 - xf);
            if(new_y1 <= y1[d[0]] + lp)
            {
                // ll d_sl = (d[0].y2 - d[0].y1)/(d[0].x2 - d[0].x1);
                ll d_sl = get_slope(d[0]);
                int lo = x1[d[0]];
                int hi = x2[d[0]];

                /*
                    find highest value of lo so that a + sl*(lo - xf) <= lp + y1[d[0]] + (lo - x1[d[0]])*d_sl
                    (sl - d_sl)*lo <= lp + y1[d[0]] - x1[d[0]]*d_sl + sl*xf
                    lo = (lp + y1[d[0]] - x1[d[0]]*d_sl + sl*xf)/(sl - d_sl)
                */

                // while(lo != hi)
                // {
                //     int mid = (lo+hi)/2 + 1;
                //     ll mid_y = lp + y1[d[0]]+ (mid-x1[d[0]])*d_sl;
                //
                //     ll new_y = a + sl*(mid - xf);
                //
                //     if(new_y <= mid_y)
                //         lo = mid;
                //     else
                //         hi = mid-1;
                // }
                if(sl == d_sl)  lo = x1[d[0]];
                else
                {
                    lo = (lp + y1[d[0]] + (-x1[d[0]])*d_sl - a + sl*xf)/(sl - d_sl);

                    assert(sl >= d_sl);
                }


                xb = max(xb, lo);

                x1[d[0]] = lo+1;
                y1[d[0]] = y2[d[0]] - (x2[d[0]] - x1[d[0]])*d_sl;

            }
        }


        if(xf <= xb)
        {
            d.push_front(new_segment(xf, a - lp, xb, a+sl*(xb-xf) - lp));
        }
    }
};



vector<func*> F(mx);
vector<func*> F2(mx);


void dfs(int u)
{
    if(u == -1) return;

    le[u] = re[u] = u;

    if(lc[u] != -1)
    {
        dfs(lc[u]);
        subtree[u] += subtree[lc[u]];
        le[u] = le[lc[u]];
    }
    if(rc[u] != -1)
    {
        dfs(rc[u]);
        subtree[u] += subtree[rc[u]];
        re[u] = re[rc[u]];
    }

    for(int q: peak_queries[u])
    {
        int lo = 0;
        int hi = sz(F[rc[u]]->d) - 1;
        while(lo != hi)
        {
            int mid = (lo+hi)/2;
            if(x2[F[rc[u]]->d[mid]] < R[q])
                lo = mid+1;
            else
                hi = mid;
        }

        auto fr = F[rc[u]];

        ll right_ans = fr->lp + y1[fr->d[lo]] + get_slope(fr->d[lo])*(R[q] - x1[fr->d[lo]]);


        ans[q] = min(ans[q], ll(H[u])*(u - L[q] + 1) + right_ans);
    }

    ll left_ct = 1;
    if(lc[u] != -1) left_ct += subtree[lc[u]];



    if(rc[u] != -1)
    {
            F[rc[u]]->inc(ll(H[u])*(u - le[u] + 1));
    }


    ll dp_u;
    if(lc[u] == -1)
    {
        dp_u = H[u];
    }
    else
    {
        dp_u = H[u] + y2[F[lc[u]]->d.back()] + F[lc[u]]->lp;
    }


    func ths;
    ths.d.push_back(new_segment(u, dp_u, u, dp_u));

    if(rc[u] != -1)
    {
        F[rc[u]]->front_AP(dp_u + H[u], H[u]);

    }

    if(lc[u] == -1 && rc[u] == -1)
    {
        F[u]->push_back(ths);
    }
    else if(lc[u] == -1)
    {
        F[u] = F[rc[u]];
        F[u]->push_front(ths);
    }
    else if(rc[u] == -1)
    {
        F[u] = F[lc[u]];
        F[u]->push_back(ths);
    }
    else
    {
        if(subtree[rc[u]] >= subtree[lc[u]])
        {
            F[u] = F[rc[u]];
            F[u]->push_front(ths);
            F[u]->push_front(*F[lc[u]]);
            F[lc[u]]->d.clear();
        }
        else
        {
            F[u] = F[lc[u]];
            F[u]->push_back(ths);
            F[u]->push_back(*F[rc[u]]);
            F[rc[u]]->d.clear();
        }
    }

    // ths->d.clear();
    ths.d.clear();
}

int rt;




vll minimum_costs(vi H_, vi L_, vi R_)
{
    // for(int f: L_) cerr << "le = " << f << '\n';
//PART 1: PROCESS INPUT

    H = H_;
    L = L_;
    R = R_;

    H_.clear();
    L_.clear();
    R_.clear();

    N = sz(H);
    Q = sz(L);

    // cerr << "queries: \n";
    // for(int j = 0; j < Q; j++) cerr << L_[j] << ' ' << R_[j] << '\n';


//PART 2: DISCRETISE HEIGHTS
    HD = vi(N);
    vector<pii> P;
    for(int i = 0; i < N; i++) P.push_back({H[i], i});
    sort(P.begin(), P.end());
    int ct = 0;
    for(pii p:P)
    {
        ct++;
        HD[p.second] = ct;
    }
    P.clear();


    // for(int j = 0; j < Q; j++) cerr << j << " : " << M[j] << '\n';

    ans = vll(Q, INF);



    for(int t = 0; t <= 1; t++)
    {

        if(t == 1)
        {
            reverse(HD.begin(), HD.end());
            reverse(H.begin(), H.end());
            for(int j = 0; j < Q; j++)
            {
                L[j] = N-1 - L[j];
                R[j] = N-1 - R[j];
                swap(L[j], R[j]);
                M[j] = N-1 - M[j];
            }
        }

        for(int i = 0; i < N; i++)
        {
            peak_queries[i].clear();
        }

        // ST = segtree(0, N-1, HD);
        if(t==0) ST.build_segtree(0, N-1, HD);
        for(int j = 0; j < Q; j++)
        {
            if(t == 0)
                M[j] = ST.rangemax(L[j], R[j]).second;
            if(M[j] == R[j])
            {
                ans[j] = min(ans[j], ll(H[M[j]])*(R[j] - L[j] + 1));
            }
            else
                peak_queries[M[j]].push_back(j);

            // cerr << "j = " << j << ": " << M[j] << '\n';
        }
        // cerr << "done A\n";

        le = vi(N, 1'000'000'000);
        re = vi(N, -1);
        if(t == 0)
        {
            // cerr << "entered\n";
            subtree = vi(N, 1);
            lc = rc = vi(N, -1);
            rt = build_tree(0, N-1);
            // cerr << "done B\n";
            // cerr << "#\n";
        }
        else
        {
            // cerr << "entered t = " << 1 << '\n';
            rt = N-1 - rt;
            vi nwl(N), nwr(N);
            for(int i = 0; i < N; i++)
            {
                if(lc[i] == -1) nwr[i] = -1;
                else nwr[i] = N-1 - lc[i];

                if(rc[i] == -1) nwl[i] = -1;
                else nwl[i] = N-1 - rc[i];
            }
            reverse(subtree.begin(), subtree.end());

            reverse(nwr.begin(), nwr.end());
            rc = nwr;

            reverse(nwl.begin(), nwl.end());
            lc = nwl;
            // cerr << "done t = 1\n";
        }

        // cerr << "\n\n\n\n\n T = " << t << '\n';
        // for(int i = 0; i < N; i++) cerr << H[i] << ' ';
        // cerr << "\n";
        // for(int i = 0; i < N; i++) cerr << HD[i] << ' ';
        // cerr << "\n";
        // for(int i = 0; i < N; i++) cerr << lc[i] << ' ';
        // cerr << "\n";
        // for(int i = 0; i < N; i++) cerr << rc[i] << ' ';
        // cerr << "\n";
        // for(int i = 0; i < N; i++) cerr << subtree[i] << ' ';
        // cerr << "\n";

        // ST.clear_tree();

        if(t == 0)
        {
            for(int i = 0; i < N; i++) F[i] = new func;
            F2 = F;
        }
        else
        {
            F = F2;
            for(int i = 0; i < N; i++)
            {
                F[i]->lp = 0;
                F[i]->d.clear();
            }
        }
        dfs(rt);

        le.clear();
        re.clear();
        lc.clear();
        rc.clear();
    }

    return ans;
}

Compilation message (stderr)

meetings.cpp: In member function 'void func::front_AP(ll, ll)':
meetings.cpp:198:17: warning: unused variable 'dx1' [-Wunused-variable]
  198 |             int dx1 = x1[d.front()];
      |                 ^~~
meetings.cpp:225:21: warning: unused variable 'hi' [-Wunused-variable]
  225 |                 int hi = x2[d[0]];
      |                     ^~
meetings.cpp:215:16: warning: unused variable 'dy1' [-Wunused-variable]
  215 |             ll dy1 = y1[d.front()] + lp;
      |                ^~~
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