제출 #1284679

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1284679		zesanul_islam	Knapsack (NOI18_knapsack)	C++20	100 / 100	38 ms	1868 KiB

knapsack

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

const int INF = -2e9;
const int MAXS = 2100;

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

    int S, N;
    cin >> S >> N;

    vector<vector<pair<int,int>>> items(S + 1); // items[w] = list of {value, count}

    // Input all items grouped by weight
    for (int i = 0; i < N; ++i) {
        int v, w, k;
        cin >> v >> w >> k;
        k = min(k, S / w); // no need for more than S/w items of this type
        items[w].push_back({v, k});
    }

    // Sort each group by value descending (to take higher-value items first)
    for (int w = 1; w <= S; ++w)
        sort(items[w].rbegin(), items[w].rend());

    // Flatten items into single list of (weight, value)
    vector<pair<int,int>> all;
    for (int w = 1; w <= S; ++w) {
        int capacity = S / w; // max items of weight w we could take
        for (auto &[v, k] : items[w]) {
            int take = min(k, capacity);
            for (int t = 0; t < take; ++t)
                all.push_back({w, v});
            capacity -= take;
            if (capacity == 0) break;
        }
    }

    // Standard 0/1 knapsack on the flattened list
    vector<int> dp(S + 1, INF);
    dp[0] = 0;

    for (auto &[w, v] : all)
        for (int s = S; s >= w; --s)
            dp[s] = max(dp[s], dp[s - w] + v);

    cout << *max_element(dp.begin(), dp.end()) << '\n';
}

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