Submission #1096239

#	Time	Username	Problem	Language	Result	Execution time	Memory
1096239		InvMOD	Knapsack (NOI18_knapsack)	C++14	73 / 100	1 ms	520 KiB

knapsack

#include<bits/stdc++.h>
 
using namespace std;
 
using ll = long long;
 
template<typename T> bool ckmx(T& a, const T& b){if(a < b) return a = b, true; return false;}
template<typename T> bool ckmn(T& a, const T& b){if(a > b) return a = b, true; return false;}
 
const int N = 2e3+5;
 
 
int S, n, w[N], v[N], k[N];
ll dp[N], answer;
vector<int> bag[N];
 
void process(int cur_w, ll cur_v){
    for(int i = S; i >= cur_w; i--){
        ckmx(dp[i], dp[i-cur_w] + cur_v);
        ckmx(answer, dp[i]);
    }
    return;
}
 
void solve()
{
    cin >> S >> n;
    for(int i = 1; i <= n; i++){
        cin >> v[i] >> w[i] >> k[i];
        if(w[i] <= S){
            bag[w[i]].push_back(i);
        }
    }
 
    for(int cur_w = 1; cur_w <= S; cur_w++){
        sort(bag[cur_w].begin(), bag[cur_w].end(), [&](int x, int y){
            return v[x] > v[y];
        });
 
        int need = S / cur_w+1, pointer = 0;
        while(pointer < (int) bag[cur_w].size() && need){
            ll cur_v = v[bag[cur_w][pointer]]; int cnt = k[bag[cur_w][pointer]];
            int can = min(need, cnt);
            need = need - can;
 
            for(int j = 0; j < (32 - __builtin_clz(can)); j++){
                if(can >= (1<<j)){
                    can -= (1<<j);
                    process(cur_w * (1<<j), cur_v * (1ll<<j));
                }
                else break;
            }
 
            if(can){
                process(cur_w * can, cur_v * (1ll * can));
            }
 
            pointer++;
        }
    }
 
    cout << answer <<"\n";
}
 
 
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
 
    #define name "task"
    if(fopen(name".INP", "r")){
        freopen(name".INP", "r", stdin);
        freopen(name".OUT", "w", stdout);
    }
 
    int t = 1; //cin >> t;
    while(t--){
        solve();
    }
    return 0;
}

Compilation message (stderr)

knapsack.cpp: In function 'int main()':
knapsack.cpp:73:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |         freopen(name".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
knapsack.cpp:74:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |         freopen(name".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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