Submission #1265791

#	Time	Username	Problem	Language	Result	Execution time	Memory
1265791		mingga	Knapsack (NOI18_knapsack)	C++20	100 / 100	28 ms	1608 KiB

knapsack

// Author: caption_mingle
#include "bits/stdc++.h"

using namespace std;

#define ln "\n"
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define ll long long
const int mod = 1e9 + 7;
const int inf = 2e9;
int dp[2005];
int n, s;

vector<pair<int, int>> d[2005];

signed main() {
	cin.tie(0) -> sync_with_stdio(0);
	#define task ""
	if(fopen(task ".INP", "r")) {
		freopen(task ".INP", "r", stdin);
		freopen(task ".OUT", "w", stdout);
	}
	vector<int> W, V;
	cin >> s >> n;
	for(int i = 1; i <= n; i++) {
		int v, w, k; cin >> v >> w >> k;
		k = min(k, s / w);
		d[w].pb({-v, k});
	} 
	for(int i = 1; i <= s; i++) {
		sort(all(d[i]));
		int lim = s / i;
		for(auto [v, k] : d[i]) {
			if(lim == 0) break;
			v = -v;
			k = min(lim, k);
			lim -= k;
			int cnt = 1; 
			while(1) {
				if(k < cnt) break;
				W.pb(cnt * i);
				V.pb(v * cnt);
				k -= cnt;
				cnt *= 2;
			}
			if(k > 0) {
				W.pb(k * i);
				V.pb(k * v);
			}
		}
	}
	for(int i = 0; i < sz(W); i++) {
		for(int j = s; j >= W[i]; j--) {
			dp[j] = max(dp[j], dp[j - W[i]] + V[i]);
		}
	}
	cout << * max_element(dp, dp + s + 1) << ln;
    cerr << "\nTime: " << clock() * 1000 / CLOCKS_PER_SEC;
}

Compilation message (stderr)

knapsack.cpp: In function 'int main()':
knapsack.cpp:24:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |                 freopen(task ".INP", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
knapsack.cpp:25:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 |                 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