Submission #630592

#	Time	Username	Problem	Language	Result	Execution time	Memory
630592		chjiao	Knapsack (NOI18_knapsack)	C++14	37 / 100	1098 ms	212 KiB

knapsack

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

int main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    // freopen("Knapsack.in", "r", stdin);
    // freopen("Knapsack.out", "w", stdout);

	int limit, type_num;
	cin >> limit >> type_num;
	
	// map<int, vector<tuple<int, int, int>>> by_weight;  //{weight, {value, amount}}, 根据weight从小到大排序

    vector<vector<int>> items(type_num, vector<int>(3));
	for (int i = 0; i < type_num; i++) {
        int weight, num, val;
        cin >> val >> weight >> num;
        if (weight>limit) continue;
        items[i][0] = weight;  items[i][1] = num;  items[i][2] = val; 
        
	}
	
    vector<int> dp(limit+1, -1);
    dp[0]= 0;

    for (int t=0; t<items.size(); t++) {
        int weight, num, val;
        weight = items[t][0]; num = items[t][1]; val = items[t][2];
        for (int j=0; j < num; j++) {
            for (int i=limit - weight; i>=0; i--) {
                
                if (dp[i]>=0) dp[i+weight] = max(dp[i+weight], dp[i] + val);
            }

        }
    }

    cout << *max_element(dp.begin(), dp.end()) << endl;
}

	// /*
	//  * best[i][j] contains the most value we can
	//  * get using j weight and the first i weight types
	//  */
	// vector<vector<ll>> best(by_weight.size() + 1, vector<ll>(limit + 1, INT32_MIN));
	// best[0][0] = 0;
	// int at = 1;
	// for (auto& [w, items] : by_weight) {
	// 	// sort items in reverse order by value
	// 	sort(items.begin(), items.end(), std::greater<pair<int, int>>());
	// 	for (int i = 0; i <= limit; i++) {
	// 		best[at][i] = best[at - 1][i];
	// 		int copies = 0;
	// 		int type_at = 0;
	// 		int curr_used = 0;
	// 		ll profit = 0;
	// 		// go through as many items until we run out of items or usable weight
	// 		while ((copies + 1) * w <= i && type_at < items.size()) {
	// 			copies++;
	// 			profit += items[type_at].first;
	// 			if (best[at - 1][i - copies * w] != INT32_MIN) {
	// 				best[at][i] = max( best[at][i],  best[at - 1][i - copies * w] + profit);
	// 			}
				
	// 			curr_used++;
	// 			if (curr_used == items[type_at].second) {
	// 				curr_used = 0;
	// 				type_at++;
	// 			}
	// 		}
	// 	}
	// 	at++;
	// }
	// cout << *std::max_element(best.back().begin(), best.back().end()) << endl;
// }

Compilation message (stderr)

knapsack.cpp: In function 'int main()':
knapsack.cpp:27:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |     for (int t=0; t<items.size(); t++) {
      |                   ~^~~~~~~~~~~~~

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