Submission #1278703

#	Time	Username	Problem	Language	Result	Execution time	Memory
1278703		jackofall718	Knapsack (NOI18_knapsack)	C++20	0 / 100	1 ms	712 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<pair<ll,ll>>> v(s + 1); // group by weight

    for (int i = 0; i < n; i++) {
        ll a, b, c;
        cin >> a >> b >> c; // value, weight, copies
        v[b].pb({a, c});
    }

    // For each weight group, keep top floor(s/weight) items
    for (int i = 1; i <= s; i++) {
        if (v[i].empty()) continue;
        // sort by value descending
        sort(v[i].rbegin(), v[i].rend());

        ll limit = s / i; // max items of this weight we could use
        ll curr = 0, it = 0;
        while (curr < limit && it < (ll)v[i].size()) {
            if (curr + v[i][it].second <= limit) {
                curr += v[i][it].second;
                it++;
            } else {
                v[i][it].second = limit - curr;
                curr = limit;
            }
        }
        if (it < (ll)v[i].size()) {
            v[i].erase(v[i].begin() + it, v[i].end());
        }
    }

    // Build query items (each copy as 0/1 item)
    vector<pair<ll,ll>> query;
    for (int i = 1; i <= s; i++) {
        for (auto &x : v[i]) {
            for (int k = 0; k < x.second; k++) {
                query.pb({x.first, i}); // (value, weight)
            }
        }
    }

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

    // 0/1 knapsack
    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);

    return 0;
}

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