Submission #480228

#	Time	Username	Problem	Language	Result	Execution time	Memory
480228		keertan	Knapsack (NOI18_knapsack)	C++17	73 / 100	1096 ms	2340 KiB

knapsack

/**
 * If you live in imaginary world when your imaginary situation encounter in 
 * real situation you can't enjoiy it because you have to do pending work.
 * {This pending work appeared because you wasted that time for your useless
 * imagianry thinking.}
 */
#include<bits/stdc++.h>
using namespace std;
//#define int  int64_t
#define all(x) x.begin(),x.end()
#define all1(x) x.rbegin(),x.rend()
#define sz(x) (int)x.size()
const int N=5e5+5;
int dp[2][2001];
 priority_queue<int> q[2001];
void solve(){
    int s,n;
    cin>>s>>n;
    vector<array<int,3>> ok(n);
    for (int i=0;i<n;i++){
        cin>>ok[i][1]>>ok[i][0]>>ok[i][2];
    }
    for (int i=0,x,y,z;i<n;i++){
        x=ok[i][0],y=ok[i][1],z=ok[i][2];
        int req=s/x;
        for (int j=1;j<=min(req,z);j++){
            q[x].push(-y);
            if (sz(q[x])>req){q[x].pop();}
        }
    }
    int u(0);
    int cur=1,prv=0;
    for (int i=1;i<=s;i++){
        while(!q[i].empty()){
            u=q[i].top();
            q[i].pop();
            u*=-1;
            for (int j=1;j<=s;j++){
                dp[cur][j]=dp[prv][j];
                if (j>=i && dp[cur][j]<dp[prv][j-i]+u){
                    dp[cur][j]=dp[prv][j-i]+u;
                }
            }
            cur^=1;
            prv^=1;
        }
    }
    int ans=0;
    for (int i=1;i<=s;i++){ans=max(ans,dp[prv][i]);}
    cout<<ans;
}
int32_t main(){
    ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
    //freopen("feast.in","r",stdin);
	//freopen("feast.out","w",stdout);
    int tq=1;
    //cin>>tq;
    for (;tq;tq--){solve();}
}
//is a bruteforce possible?
//think greedier, make more assumptions
// if we you find solution using loop to decrease complexity use bs
//stuck for more than 5 minutes? move on 

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