Submission #693380

#	Time	Username	Problem	Language	Result	Execution time	Memory
693380		vjudge1	Knapsack (NOI18_knapsack)	C++17	37 / 100	2 ms	468 KiB

knapsack

#include <bits/stdc++.h>
using namespace std;

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

    int W, n;
    cin >> W >> n;
    vector<array<long long, 2>> a; // { (value, weight) }
    vector<vector<array<int, 2>>> mp(W + 1);

    for (int i = 0; i < n; i++) {
        long long v, w;
        int cnt;
        cin >> v >> w >> cnt;
        mp[w].push_back({v, cnt});
    }

    for (int w = 1; w <= W; w++) {
        sort(mp[w].begin(), mp[w].end(), greater<>());
        int needed = W / w;
        int i = 0;
        while (i < (int)mp[w].size() && needed > 0) {
            auto [v, cnt] = mp[w][i];
            needed -= cnt;

            int hbp = 31 - __builtin_clz(cnt);
            for (int k = 0; k < hbp; k++) {
                a.push_back({ v * (1 << k), w * (1 << k) });
            }
            cnt -= (1 << hbp) - 1;
            for (int k = 0; k < 31; k++) {
                if (cnt >> k & 1) {
                    a.push_back({ v * (1 << k), w * (1 << k) });
                }
            }

            i++;
        }
    }

    n = a.size();

    vector<long long> dp(W + 1, 0);

    for (int i = 1; i <= n; i++) {
        for (int w = W; w >= a[i - 1][1]; w--) {
            dp[w] = max( dp[w], dp[w - a[i - 1][1]] + a[i - 1][0] );
        }
    }

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

Compilation message (stderr)

knapsack.cpp: In function 'int main()':
knapsack.cpp:17:26: warning: narrowing conversion of 'v' from 'long long int' to 'int' [-Wnarrowing]
   17 |         mp[w].push_back({v, cnt});
      |                          ^

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