Submission #1255638

#	Time	Username	Problem	Language	Result	Execution time	Memory
1255638		vuviet	Festival (IOI25_festival)	C++20	100 / 100	88 ms	31524 KiB

festival

/**
 *  __      __   __      __
 *  \ \    / /   \ \    / (_)     _____
 *   \ \  / /_   _\ \  / / _  ___|_   _|
 *    \ \/ /| | | |\ \/ / | |/ _ \ | |
 *     \  / | |_| | \  /  | |  __/ | |
 *      \/   \__,_|  \/   |_|\____||_|
 *
 *     Author:    VuViet
 *     Created:   2025-08-09 19:44
**/

#include <bits/stdc++.h>

using namespace std;

const int N = 1e6 + 6;

struct Item 
{
    long long p, t, idx;
} items[N];
long long l_id, r_id, A;
int n;

bool cmp(Item a, Item b) 
{
    if (a.t == b.t && a.t == 1)
        return a.p < b.p;
    long long c1 = 1LL * a.p * a.t * (b.t - 1);
    long long c2 = 1LL * b.p * b.t * (a.t - 1);
    return c1 < c2;
}

vector<int> res, chosen[N / 5]; 
vector<long long> dp;

void DFS(long long pos, long long cnt) 
{
    if (pos < l_id || cnt == 0) return;
    if (chosen[pos][cnt]) 
    {
        DFS(pos - 1, cnt - 1);
        res.push_back(items[pos].idx);
    } else {
        DFS(pos - 1, cnt);
    }
}

void Init(vector<int> P, vector<int> T) 
{
    n = (int)P.size();
    for (int i = 0; i < n; i++) {
        items[i] = {1LL * P[i], 1LL * T[i], i };
    }
    sort(items, items + n, cmp);
    r_id = n;
    while (r_id > 0 && items[r_id - 1].t == 1)
        r_id--;
    l_id = r_id;
}

bool Greedy(long long &A) 
{
    res.clear();
    for (int i = 0; i < r_id; i++) 
        if ((A - items[i].p) * items[i].t >= A) 
        {
            A = ((A - items[i].p) * items[i].t);
            res.push_back(items[i].idx);
            if (A > 1e16) 
            {
                res.clear();
                for (int j = 0; j < n; j++)
                    res.push_back(items[j].idx);
                return true;
            }
        } else {
            l_id = i;
            break;
        }
    return false;
}

void DP(long long A) 
{
    dp.clear();
    dp.push_back(A);
    for (long long i = l_id; i < r_id; i++) 
    {
        int sz = (int)dp.size();
        chosen[i].resize(sz, 0);
        if ((dp[sz - 1] - items[i].p) * items[i].t >= 0) 
        {
            dp.push_back((dp[sz - 1] - items[i].p) * items[i].t);
            chosen[i].push_back(1);
        }
        for (int j = sz - 2; j >= 0; j--) 
        {
            long long val = (dp[j] - items[i].p) * items[i].t;
            if (val > dp[j + 1]) 
            {
                dp[j + 1] = val;
                chosen[i][j + 1] = 1;
            }
        }
    }
}

long long FindBest() 
{
    long long maxCount = 0, pos = 0;
    for (int i = 0; i < (int)dp.size(); i++) 
    {
        long long lo = r_id, hi = n - 1, cnt = 0;
        while (lo < hi) 
        {
            long long mid = (lo + hi + 1) / 2;
            if (dp[i] >= items[mid].p) 
            {
                cnt = (mid - r_id + 1);
                lo = mid;
            } else {
                hi = mid - 1;
            }
        }
        if (i + cnt > maxCount) 
        {
            maxCount = i + cnt;
            pos = i;
        }
    }
    return pos;
}

vector<int> max_coupons(int a, vector<int> P, vector<int> T) 
{
    A = a;
    Init(P, T);
    if (Greedy(A)) return res;
    for (int i = r_id + 1; i < n; i++) {
        items[i].p += items[i - 1].p;
    }
    DP(A);
    int pos = FindBest();
    DFS(r_id - 1, pos);
    long long remain = dp[pos];
    for (int i = n - 1; i > r_id; i--) {
        items[i].p -= items[i - 1].p;
    }
    for (int i = r_id; i < n; i++) 
        if (remain >= items[i].p) 
        {
            remain -= items[i].p;
            res.push_back(items[i].idx);
        }
    return res;
}

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 15 / 15
• Subtask 5: 27 / 27
• Subtask 6: 16 / 16
• Subtask 7: 18 / 18