Submission #1293509

#	Time	Username	Problem	Language	Result	Execution time	Memory
1293509		haha	Feast (NOI19_feast)	C++20	In queue	0 ms	0 KiB

feast

#include <bits/stdc++.h>
#define f first
#define s second
#define ll long long
using namespace std;
const int maxn=1e7+5;
const int MOD=1e9+7;

int n,k;
vector<int> a;
vector<ll> sum,Max;
vector<vector<ll>> dp;

void sub1(){
    if(k==n){
        ll tong = 0;
        for(int i = 1;  i <= n; i++){
            tong = tong + a[i];
        }
        cout << tong << endl;
        return;
    }
    long long tong = 0;
    for(int i = 1; i <= n; i++){
        if(a[i] > 0){
            tong = tong + a[i];
        }
    }
    cout << tong << endl;
    return;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    cin>>n>>k;
    a.assign(n+5,0);
    sum.assign(n+5,0);
    int cnt=0,pos=0;
    for(int i=1;i<=n;i++){
        cin>>a[i];
        sum[i]=sum[i-1]+a[i];
        if(a[i]<0){
            cnt++;
            pos=i;
        }
    }
    ll ans=-1e18;
    if(cnt<=1&&k!=1){
        sub1();
    }
    else{
        dp.assign(n+5,vector<ll>(k+5,-1e18));
        Max.assign(n+5,0);
        for(int i=0;i<=n;i++) dp[i][0]=0;
        for(int i=1;i<=n;i++){
            Max[i]=max(Max[i-1],-sum[i]);
        }
        for(int x=1;x<=k;x++){
            for(int i=1;i<=n;i++){
                dp[i][x]=dp[i-1][x];
                dp[i][x]=max(dp[i][x],Max[i-1]+sum[i]);
            }
            Max[0]=-1e18;
            for(int i=1;i<=n;i++){
                Max[i]=max(Max[i-1],dp[i][x]-sum[i]);
            }
        }
        for(int i=1;i<=n;i++) ans=max(ans,dp[i][k]);
        cout<<ans;
    }
}