Submission #863134

#	Time	Username	Problem	Language	Result	Execution time	Memory
863134		Kodik	Knapsack (NOI18_knapsack)	C++17	100 / 100	72 ms	35192 KiB

knapsack

#include <bits/stdc++.h>
using namespace std;
//
// #define xx real()
// #define yy imag()
//
#define ff first
#define ss second
//
typedef long long  ll;
typedef long double ld;
// typedef complex<ld> point;

void sieve(int n, vector<bool>& is_composite, vector<int>& prime) {
	for (int i = 2; i < n; ++i) {
		if (!is_composite[i]) prime.push_back(i);
		for (int j = 0; j < int(prime.size()) && i * prime[j] < n; ++j) {
			is_composite[i * prime[j]] = true;
			if (i % prime[j] == 0) break;
		}
	}
}


void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}



int main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    // setIO("shuffle");
	int limit, type_num;
	cin >> limit >> type_num;
	map<int, vector<pair<int,int>>> by_weight;
	for(int i = 0; i < type_num; ++i){
		int value, weight, amt;
		cin >> value >> weight >> amt;
		if(weight <= limit && amt > 0){
			by_weight[weight].push_back({value, amt});
		}
	}
	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.begin(), items.end(), 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;
			ll profit = 0;
			while((copies+1)*w<=i&&type_at<items.size()){
				++copies;
				profit += items[type_at].ff;
				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].ss){
					curr_used = 0;
					++type_at;
				}
			}
		}
		++at;
	}
	cout << *max_element(best.back().begin(), best.back().end()) << '\n';
	return 0;
}

Compilation message (stderr)

knapsack.cpp: In function 'int main()':
knapsack.cpp:54:34: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |    while((copies+1)*w<=i&&type_at<items.size()){
      |                           ~~~~~~~^~~~~~~~~~~~~
knapsack.cpp: In function 'void setIO(std::string)':
knapsack.cpp:26:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
knapsack.cpp:27:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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