Submission #693018

#	Time	Username	Problem	Language	Result	Execution time	Memory
693018		vjudge1	Knapsack (NOI18_knapsack)	C++17	100 / 100	98 ms	35144 KiB

knapsack

#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <fstream>
#include <cassert>
#include <cstring>
#include <unordered_set>
#include <unordered_map>
#include <numeric>
#include <ctime>
#include <bitset>
#include <complex>
#include <chrono>
#include <random>
#include <functional>
#define taskname "D"

using namespace std;

mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

long long Rand(long long l, long long r)
{
    return uniform_int_distribution<long long>(l, r)(rng);
}

struct perf
{
    chrono::steady_clock::time_point start_;
    perf() : start_(chrono::steady_clock::now()) {}
    double elapsed() const
    {
        auto stop = chrono::steady_clock::now();
        chrono::duration<double> elapsed_seconds = stop - start_;
        return elapsed_seconds.count();
    }
};

void solve()
{
    int limit;
    int type_num;
    cin >> limit >> type_num;

    map<int, vector<pair<int, int>>> weights;
    for (int t = 0; t < type_num; t++)
    {
        int value;
        int weight;
        int amt;
        cin >> value >> weight >> amt;
        if (weight <= limit && amt > 0)
        {
            weights[weight].push_back({value, amt});
        }
    }
    vector<vector<long long>> best(
        weights.size() + 1, vector<long long>(limit + 1, INT32_MIN));
    best[0][0] = 0;
    int at = 1;
    for (auto &[w, items] : weights)
    {
        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;
            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 << *max_element(best.back().begin(), best.back().end()) << endl;
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    if (fopen(taskname ".inp", "r"))
    {
        freopen(taskname ".inp", "r", stdin);
        freopen(taskname ".out", "w", stdout);
    }
    int t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
    }
}

Compilation message (stderr)

knapsack.cpp: In function 'void solve()':
knapsack.cpp:79:53: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |             while ((copies + 1) * w <= i && type_at < items.size())
      |                                             ~~~~~~~~^~~~~~~~~~~~~~
knapsack.cpp: In function 'int main()':
knapsack.cpp:110:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  110 |         freopen(taskname ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
knapsack.cpp:111:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |         freopen(taskname ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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