Submission #1278704

#	Time	Username	Problem	Language	Result	Execution time	Memory
1278704		jackofall718	Knapsack (NOI18_knapsack)	C++20	0 / 100	1 ms	572 KiB

knapsack

#include <bits/stdc++.h>
#include <chrono>
#define ll long long int
#define endl '\n'
#define vn vector<ll>
#define vi vector<pair<ll,ll>>

using namespace std;
using namespace std::chrono;
const int MAX_N = 1e9 + 7;
#define pii pair<ll,ll>
const ll INF = 0x3f3f3f3f3f3f3f3f;

#define pb push_back  
#define srt(vp) sort(vp.begin(), vp.end()) 

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    auto start = high_resolution_clock::now();

    ll s, n;
    cin >> s >> n;
    vector<vector<ll>> v(s + 1); // group by weight, store values only

    for (int i = 0; i < n; i++) {
        ll a, b, c;
        cin >> a >> b >> c; // value, weight, copies
        if (b > s) continue; // weight too big, ignore
        for (int k = 0; k < c && k < (s / b); k++) {
            v[b].pb(a); 
        }
    }

    // Now limit per weight group to top floor(s/w) values
    vector<pair<ll,ll>> query; // (value, weight)
    for (int w = 1; w <= s; w++) {
        if (v[w].empty()) continue;
        sort(v[w].rbegin(), v[w].rend());
        ll limit = s / w;
        if ((ll)v[w].size() > limit) v[w].resize(limit);
        for (auto val : v[w]) {
            query.pb({val, w});
        }
    }

    vn dp(s + 1, -1);
    dp[0] = 0;

    // 0/1 knapsack on reduced set
    for (auto &q : query) {
        ll val = q.first, w = q.second;
        for (int j = s; j >= w; j--) {
            if (dp[j - w] != -1) {
                dp[j] = max(dp[j], dp[j - w] + val);
            }
        }
    }

    cout << dp[s] << endl;

    auto stop = high_resolution_clock::now();
    auto duration = duration_cast<microseconds>(stop - start);
    // cerr << "Time: " << duration.count() << " us\n"; // debug timing if needed

    return 0;
}

• Subtask 1: 0 / 12
• Subtask 2: 0 / 17
• Subtask 3: 0 / 20
• Subtask 4: 0 / 24
• Subtask 5: 0 / 27