Submission #802406

#	Time	Username	Problem	Language	Result	Execution time	Memory
802406		nixa	Knapsack (NOI18_knapsack)	C++17	100 / 100	87 ms	36372 KiB

knapsack

#include <bits/stdc++.h> 
 
using namespace std;

#define ll long long
#define pll pair<long long, long long> 
#define vll vector<ll> 
#define fi first
#define sc second
#define ld long double
#define pb push_back

const ll mod = 1e9 + 7;

int chngi[] = {0, 0, 1, -1};
int chngj[] = {1, -1, 0, 0}; 
char chng[] = {'R', 'L', 'D', 'U'}; 

ll add(ll a, ll b){ 
    a += b;
    if(a >= mod) a-=mod; 
    return a; 
}

ll sub(ll a, ll b){ 
   return ((a % mod) - (b % mod) + mod) % mod; 
}

ll mul(ll a, ll b){
    return (a*b)%mod; 
}

void usaco_submit(string s){
    string in = s + ".in";
    string out = s + ".out"; 

    const char* sin = in.c_str();
    const char* sout = out.c_str();

    freopen(sin, "r", stdin);
    freopen(sout, "w", stdout);
}



//! CODE FROM HERE


int main(){
    // usaco_submit("stacking"); 

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll tc= 1; 

    // ll tc;
    // cin>>tc;
    while(tc--){
        ll n, s;
        cin>>s>>n;

        map<ll, vector<pll> > wts; 

        for(int i = 0; i<n; i++){ 
            ll val, wt, amt;
            cin>>val>>wt>>amt;

            if(wt <= s && amt > 0){
                wts[wt].push_back({val, amt}); 
            }
        }   

        vector<vector<ll> > dp(wts.size() +1, vector<ll> (s+1, INT_MIN)); 

        dp[0][0] = 0;
        ll i = 1; 

        for(auto &[wt, items]: wts){ 

            sort(items.begin(), items.end(), greater<pll>()); 
            ll total_items = items.size(); 

            for(ll cw = 0; cw <= s; cw++){ 
                dp[i][cw] = dp[i-1][cw];
                ll curr = 0; 
                ll copies_taken = 0; 
                ll val = 0; 
                ll curr_taken = 0; 

                while((copies_taken+1)*wt <= cw && curr < total_items){ 
                    copies_taken++; 
                    curr_taken++; 

                    val += items[curr].first; 
                    if(dp[i-1][cw - copies_taken*wt] != INT_MIN){  
                        dp[i][cw] = max(dp[i][cw], 
                                                        dp[i-1][cw - copies_taken*wt] + val); 
                    }   

                    if(items[curr].second == curr_taken){
                        curr_taken = 0; 
                        curr++; 
                    }
                }
            }
            i++; 
        }

        cout << *max_element(dp.back().begin(), dp.back().end()) << endl;
    } 
     


    return 0; 
}

Compilation message (stderr)

knapsack.cpp: In function 'void usaco_submit(std::string)':
knapsack.cpp:40:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |     freopen(sin, "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~
knapsack.cpp:41:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |     freopen(sout, "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~

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