Submission #492448

#	Time	Username	Problem	Language	Result	Execution time	Memory
492448		Psudora	Knapsack (NOI18_knapsack)	C++17	100 / 100	101 ms	37496 KiB

knapsack

#include <bits/stdc++.h> 
using namespace std;       
#define ll long long 
const int mod = 1000000007; 
const int INF = 1e9; 
const int N = (int)1e5+5; 
vector<int>adj[N]; 

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);  
    // 
    int limit, type_num;
	cin >> limit >> type_num;
	
	map<int, vector<pair<int, int>>> by_weight;
	for (int t = 0; t < type_num; t++) {
		int value, weight, amt;
		cin >> value >> weight >> amt;
		if (weight <= limit && amt > 0) {
			by_weight[weight].push_back({value, amt});
		}
	} 
	vector<vector<long long>> best(by_weight.size() + 1, vector<long long>(limit + 1, INT32_MIN));
	best[0][0] = 0;
	int at = 1;
	for (auto& [w, items] : by_weight) { 
		std::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, type_at = 0, curr_used = 0;
			long long profit = 0; 
			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] = std::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;
	return 0;
}

Compilation message (stderr)

knapsack.cpp: In function 'int main()':
knapsack.cpp:33:44: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |    while ((copies + 1) * w <= i && type_at < items.size()) {
      |                                    ~~~~~~~~^~~~~~~~~~~~~~

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