Submission #729421

#	Time	Username	Problem	Language	Result	Execution time	Memory
729421		josanneo22	Knapsack (NOI18_knapsack)	C++17	100 / 100	108 ms	35144 KiB

knapsack

#include<bits/stdc++.h>
#include<iostream>
#include<stdlib.h>
#include<cmath>
#include <algorithm>
#include<numeric>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pair<int, int> > vpii;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;
typedef vector<ll> vll;
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define trav(a,x) for (auto& a: x)
#define fr(i, a, b, s) for (int i=(a); (s)>0?i<(b):i>=(b); i+=(s))
#define mp make_pair
#define pb push_back
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define in insert
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define out(x) cout<<x<<'\n'
int dx[4] = { -1, 0, 1, 0 };
int dy[4] = { 0, 1, 0, -1 };
int dx8[8]={0,0,-1,1,-1,1,-1,1};
int dy8[8]={-1,1,0,0,-1,1,1,-1};
void solve(){
    int limit,type_num; cin >> limit >> type_num; 
	unordered_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});
		}
	}
	/*
	 * best[i][j] contains the most value we can
	 * get using j weight and the first i weight types
	 */
	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) { 
        sort(all(items),greater<pii>());
		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;
			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] = 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;
}
signed main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	int tt=1;// cin>>tt;
	while(tt--){
		solve();
	}
}

Compilation message (stderr)

knapsack.cpp: In function 'void solve()':
knapsack.cpp:58:44: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   58 |    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