Submission #1175318

#	Time	Username	Problem	Language	Result	Execution time	Memory
1175318		pete555	Knapsack (NOI18_knapsack)	C++17	100 / 100	36 ms	1984 KiB

knapsack

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

#define pi pair<int,int>
#define ll long long
#define pb push_back
#define pf push_front

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

const int MOD = 1e9+7;

int main()
{
	cin.tie(0)->sync_with_stdio(false);
	//fileIO("");
	int S, n;
	cin >> S >> n;
	unordered_map<int,vector<pi>> m;
	for(int i=0; i<n; i++){
		int v, w, k;
		cin >> v >> w >> k;
		m[w].pb({v, k});
	}
	vector<int> dp(S+1);
	for(auto I: m){ // 1 <= w <= S
		sort(I.second.begin(), I.second.end(), greater<pi>());
		int w = I.first;
		for(int i=S; i>=0; i--){
			int cnt = 0, idx = 0, used = 0, profit = 0;
			while((cnt+1)*w <= i and idx < I.second.size()){
				cnt++, used++;
				profit += I.second[idx].first;
				dp[i] = max(dp[i], dp[i-cnt*w] + profit);
				if(used == I.second[idx].second){
					used = 0;
					idx++;
				}
			}
		}
	}
	cout << dp[S] << '\n';
}

Compilation message (stderr)

knapsack.cpp: In function 'void fileIO(std::string)':
knapsack.cpp:10:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 |         freopen((filename + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
knapsack.cpp:11:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |         freopen((filename + ".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