Submission #1201897

#	Time	Username	Problem	Language	Result	Execution time	Memory
1201897		durgeshh	Knapsack (NOI18_knapsack)	C++20	100 / 100	62 ms	34376 KiB

knapsack

#include <bits/stdc++.h>
#define Task "Task"
#define ll long long
#define vii vector<pair<ll,ll>>
using namespace std;

int n,S,w,v,k;
map<int,vii> by_weight;

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    if (fopen(Task".inp","r")) {
        freopen(Task".inp","r",stdin);
        freopen(Task".out","w",stdout);
    }
    
    cin >> S >> n;
    for(int i = 0; i < n; i++) {
        cin >> v >> w >> k;
        if (w <= S && k > 0) by_weight[w].push_back({v,k});
    }
    
    vector<vector<ll>> best(by_weight.size() + 1, vector<ll> (S + 1, -1e9));
    // best[i][j]: best value u can get by using first i types, and j weights
    best[0][0] = 0;
    int at = 1;
    for(auto &[w, items]: by_weight) {
        sort(items.begin(), items.end(),greater<pair<ll,ll>>());
        for(int j = 0; j <= S; j++) {
            best[at][j] = best[at-1][j];
            ll profit = 0;
            int type_at = 0;
            int copies = 0;
            int curr_used = 0;
            while((copies + 1) * w <= j && type_at < items.size()) {
                ++copies;
                profit += items[type_at].first;
                best[at][j] = max(best[at][j], best[at-1][j - copies * w] + profit);

                curr_used++;
                if (curr_used == items[type_at].second) {
                    curr_used = 0;
                    type_at++;
                }
            }
        }
        at++;
    } 

    cout << *max_element(best.back().begin(), best.back().end());
    return 0;
}

Compilation message (stderr)

knapsack.cpp: In function 'int main()':
knapsack.cpp:14:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |         freopen(Task".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
knapsack.cpp:15:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |         freopen(Task".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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