Submission #1129614

#TimeUsernameProblemLanguageResultExecution timeMemory
1129614shivansh0809Holiday (IOI14_holiday)C++17
100 / 100
347 ms47776 KiB
#include "holiday.h"
#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for(int i = a;i < b;i++)
#define pii pair<int,int>
#define all(v) v, v+n
#define vi vector<int>

const int N = 100'005;
const int LN = 20;

struct PersistentSegTree
{ // Returns the sum of K largest elements in [l, r)
    map<int,pii> cp;
    // add log2(Q) is storage needed after some update query
    int L[LN*N],R[LN*N],S[LN*N]; long long KS[LN*N];
    int SZ = 1, roots[N], MX;
    PersistentSegTree(int v[], int n) : MX(n) {
        int tl = 0, tr = n, idx[n];pii sort_v[n];
        rep(i, 0, n) sort_v[i] = {v[i], i};
        sort(all(sort_v), greater<pii>());
        rep(i,0,n)cp[i]=sort_v[i],idx[sort_v[i].second]=i;
        roots[0] = build(tl, tr);
        rep(i,0,n)roots[i+1]=update(roots[i],tl,tr,idx[i]);
    }
    int ver(int s, int ks, int l, int r) {
        S[SZ]=s;KS[SZ]=ks;L[SZ]=l;R[SZ]=r;return SZ++;
    }
    int ver(int l, int r) {
        S[SZ]=S[l]+S[r];KS[SZ]=KS[l]+KS[r];
        L[SZ]=l;R[SZ]=r;return SZ++;
    }
    int build(int tl, int tr){
        if (tl == tr) return ver(0, 0, -1, -1);
        int tm = (tl+tr)/2;
        return ver(build(tl, tm),build(tm + 1, tr));
    }
    int update(int idx, int tl, int tr, int pos){
        if (tl == tr)
            return ver(S[idx]+1,KS[idx]+cp[pos].first,-1,-1);
        int tm = (tl + tr) / 2;
        if (pos <= tm)
        return ver(update(L[idx],tl,tm,pos),R[idx]);
        return ver(L[idx],update(R[idx],tm+1,tr,pos));
    }
    long long kth(int vl, int vr, int tl, int tr, int k) {
        if (tl == tr) return KS[vr]-KS[vl];
        int tm = (tl+tr)/2,lc=S[L[vr]]-S[L[vl]];
        if (lc >= k)return kth(L[vl], L[vr], tl, tm, k);
        return KS[L[vr]]-KS[L[vl]]+kth(R[vl], 
            R[vr],tm+1,tr,k-lc);
    }
    long long kth(int l, int r, int k) {
        return kth(roots[l], roots[r], 0, MX, k);
    }
};


long long int findMaxAttraction(int n, int start, int d, int attraction[])
{
    long long int ans = 0;
    PersistentSegTree pst(attraction, n);
    function<long long(int, int)> C1 = [&](int k, int mid) -> long long
    {
        int days_rem = d - (mid - k + start - k);
        if (days_rem <= 0)
            return 0;
        return pst.kth(k, mid + 1, days_rem);
        // return mid - k;
    };
    function<long long(int, int)> C2 = [&](int mid, int k) -> long long
    {
        int days_rem = d - (k - mid + k - start);
        if (days_rem <= 0)
            return 0;
        return pst.kth(mid, k + 1, days_rem);
        // return k - mid;
    };

    // function<void(int, int, int, int)> dncg = [&](int l, int r, int optl, int optr)
    // {
    //     if (l > r)
    //         return;

    //     int mid = (l + r) >> 1;
    //     pair<long long, int> best = {-1, -1};

    //     for (int k = optl; k <= min(mid, optr); k++)
    //         best = max(best, {C1(k, mid), k});

    //     // debug(dp, best, ndp);
    //     // debug(ans, best, mid);
    //     ans = max(best.first, ans);
    //     int opt = best.second;

    //     dncg(l, mid - 1, optl, opt);
    //     dncg(mid + 1, r, opt, optr);
    // };
    // function<void(int, int, int, int)> dncs = [&](int l, int r, int optl, int optr)
    // {
    //     if (l > r)
    //         return;

    //     int mid = (l + r) >> 1;
    //     pair<long long, int> best = {-1, -1};

    //     for (int k = optr; k >= max(mid, optl); k--)
    //         best = max(best, {C2(mid, k), k});

    //     // debug(dp, best, ndp);
    //     // debug(ans, best, mid);
    //     ans = max(best.first, ans);
    //     int opt = best.second;

    //     dncs(l, mid - 1, optl, opt);
    //     dncs(mid + 1, r, opt, optr);
    // };
    if (d == 0)
        return 0;
    ans = attraction[start];
    vector<array<int, 4>> dncg, dncs;
    dncg.push_back({start + 1, n - 1, 0, start});
    dncs.push_back({0, start - 1, start, n - 1});
    while (!dncg.empty())
    {
        auto [l, r, optl, optr] = dncg.back();
        dncg.pop_back();
        if (l > r)
            continue;

        int mid = (l + r) >> 1;
        pair<long long, int> best = {-1, -1};

        for (int k = optl; k <= min(mid, optr); k++)
            best = max(best, {C1(k, mid), k});

        // debug(dp, best, ndp);
        // debug(ans, best, mid);
        ans = max(best.first, ans);
        int opt = best.second;

        dncg.push_back({mid + 1, r, opt, optr});
        dncg.push_back({l, mid - 1, optl, opt});
    }
    while (!dncs.empty())
    {
        auto [l, r, optl, optr] = dncs.back();
        dncs.pop_back();
        if (l > r)
            continue;

        int mid = (l + r) >> 1;
        pair<long long, int> best = {-1, -1};

        for (int k = optr; k >= max(mid, optl); k--)
            best = max(best, {C2(mid, k), k});

        // debug(dp, best, ndp);
        // debug(ans, best, mid);
        ans = max(best.first, ans);
        int opt = best.second;
        dncs.push_back({mid + 1, r, opt, optr});
        dncs.push_back({l, mid - 1, optl, opt});
    }
    // dncg(start + 1, n - 1, 0, start);
    // dncs(0, start - 1, start, n - 1);

    return ans;
}
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