Submission #1220992

#	Time	Username	Problem	Language	Result	Execution time	Memory
1220992		longgggg	Knapsack (NOI18_knapsack)	C++17	37 / 100	1 ms	328 KiB

knapsack

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'

#define IN "A.in"
#define OUT "A.out"
#define DEBUG "debug.out"

const int mxN = 100005, INF = (int) 1e9+5;
const ll MOD = (ll) 1e9+7, LINF = (ll) 1e18;

void solve() {
    int n, limit; cin >> limit >> n;

    // (v, w) got k times
    map <pair <int, int>, int> a; 
    for (int i = 1; i <= n; i++) {
        int v, w, k; cin >> v >> w >> k;
        a[{v, w}] += k;
    }
    // Binary Decomposition
    vector <pair <int, int>> items; // (w, v)
    for (auto &x : a) {
        int w = x.first.second, v = x.first.first, k = x.second;
        for (int curr_copy = 1; k > 0; curr_copy <<= 1) { // d *= 2
            int use = min(curr_copy, k);
            items.push_back({w * use, v * use});
            k -= use;
        }
    }
    // for (auto &x : items) cerr << x.first << " " << x.second << endl;

    vector <ll> dp(limit + 1, 0);
    for (auto &it : items) {
        int w = it.first, v = it.second;
        for (int j = limit; j >= w; j--) {
            dp[j] = max(dp[j], dp[j - w] + v);
        }
    }

    cout << dp[limit] << endl;
}

signed main() {
    if (fopen(IN, "r")) {
        freopen(IN, "r", stdin);
        freopen(OUT, "w", stdout);
        freopen(DEBUG, "w", stderr);
    }

    ios_base::sync_with_stdio(0); cin.tie(0);

    // ll t; cin >> t;
    // while (t--)
    solve();
}

Compilation message (stderr)

knapsack.cpp: In function 'int main()':
knapsack.cpp:47:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |         freopen(IN, "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~
knapsack.cpp:48:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |         freopen(OUT, "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~
knapsack.cpp:49:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |         freopen(DEBUG, "w", stderr);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 12
• Subtask 2: 17 / 17
• Subtask 3: 20 / 20
• Subtask 4: 0 / 24
• Subtask 5: 0 / 27