Submission #791337

#	Time	Username	Problem	Language	Result	Execution time	Memory
791337		vjudge1	Feast (NOI19_feast)	C++14	30 / 100	27 ms	5000 KiB

feast

//#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC target("bmi,bmi2,lzcnt,popcnt")
//#pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma,tune=native")
//#pragma expected_value
//#pragma isolated_call
//#pragma disjoint

#include<bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>

//using namespace __gnu_pbds;
using namespace std;

#define int long long
//#define double long double
#define Fi first
#define Se second
#define Rep(i,a,b) for (int i=a;i<=b;++i)
#define Repu(i,b,a) for (int i=b;i>=a;--i)
#define pb push_back
#define ms(a,i) memset(a,i,sizeof(a))
#define sz size()
#define mp make_pair
#define endl '\n'
#define sef setprecision(6)<<fixed
#define cer cout<<"cak"<<endl;

typedef pair<int,int> ii;
typedef vector<int> vi;
typedef vector<double> va;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef vector<va> vva;

//const double EPS=1e-9;
const double PI=acos(-1);
const long long oo=1e18;
const int MN=3e5+5;
const int mod=1e9+7;

using cd=complex<double>;

//typedef tree<int,null_type,less<int>,rb_tree_tag, tree_order_statistics_node_update> index_set;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n,k;
int a[MN];

struct Node {
	int pref =0, suff = 0;
	int sum = 0;
	int ans = 0;
};

Node base;

Node merge(Node a, Node b) {
	Node c;
	c.ans = max(a.ans, b.ans);
	c.ans = max(c.ans, a.suff + b.pref);
	c.pref = max(a.pref, a.ans + b.pref); c.suff = (b.suff, a.suff + b.sum);
	c.sum = a.sum + b.sum;
	return c;
}

Node st[4*MN];

void build(int id,int l,int r) {
	if(l==r) {
		st[id].sum = a[l];
		int temp = 0;
		if(temp < a[l]) temp = a[l];
		st[id].ans = temp; st[id].pref = temp; st[id].suff = temp;
		return;
	}
	int mid = (l+r)/2;
	build(id*2,l,mid); build(id*2+1,mid+1,r);
	st[id] = merge(st[id*2], st[id*2+1]);
}

Node get(int id,int l,int r,int u,int v) 
{
	if(l>v or r<u) return base;
	if(u<=l and v>=r) return st[id];
	int mid = (l+r)/2;
	return merge(get(id*2,l,mid,u,v), get(id*2+1,mid+1,r,u,v));
}

int dp_before[MN], dp_now[MN];

void compute(int l,int r,int tl,int dr) {
	if(l>r) return;
	int mid = (l+r)/2;
	ii maxx = {dp_before[mid], mid};
	Rep(i,tl,min(dr,mid-1)) {
		int temp = get(1,1,n,i+1,mid).ans;
		maxx = max(maxx, ii(dp_before[i] + temp,i));
	}

	dp_now[mid] = maxx.Fi;
	compute(l,mid-1,tl,maxx.Se); compute(mid+1,r,maxx.Se,dr);
}

signed main() {
  	//freopen(".inp","r",stdin); freopen(".out","w",stdout);
  	
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	cin>>n>>k;
	if(n<=2000) {
		Rep(i,1,n) cin>>a[i];
		build(1,1,n);

		Rep(i,1,n) dp_before[i] = get(1,1,n,1,i).ans;
		Rep(i,2,k) {
			compute(1,n,1,n);
			Rep(j,1,n) dp_before[j] = dp_now[j]; 
		}

		cout<<dp_before[n];
		return 0;
	}

	int cnt = 0;
	Rep(i,1,n) {
		cin>>a[i];
		if(a[i] < 0) cnt++;
	}

	if(cnt == 0) {
		int sum = 0;
		Rep(i,1,n) {
			sum += a[i];
		}
		cout<<sum;
		return 0;
	}

	else {
		if(k==1) {
			int ans = 0;
			Rep(i,1,n) {
				dp_now[i] = max(dp_now[i-1] + a[i], a[i]);
				ans = max(ans,dp_now[i]);
			}
			cout<<ans;
		}
		else {
			int sum = 0;
			Rep(i,1,n) {
				if(a[i]<0) continue;
				sum += a[i];
			}
			cout<<sum;
		}
	}
}

Compilation message (stderr)

feast.cpp: In function 'Node merge(Node, Node)':
feast.cpp:62:52: warning: left operand of comma operator has no effect [-Wunused-value]
   62 |  c.pref = max(a.pref, a.ans + b.pref); c.suff = (b.suff, a.suff + b.sum);
      |                                                  ~~^~~~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 0 / 10
• Subtask 5: 0 / 11
• Subtask 6: 0 / 20
• Subtask 7: 0 / 29