Submission #226295

#	Time	Username	Problem	Language	Result	Execution time	Memory
226295		bharat2002	Split the sequence (APIO14_sequence)	C++14	0 / 100	69 ms	131072 KiB

sequence

/*input
7 3
4 1 3 4 0 2 3
*/
#include<bits/stdc++.h>
using namespace std;
const int N=1e5 + 100;
const int mod=1e9 + 7;
#define int long long
const int inf=1e18;
#define pii pair<int, int>
#define f first
#define s second 
#define mp make_pair
#define FOR(i, n) for(int i=1;i<=n;i++)
#define TRACE(x) cerr << #x << " = " << x << endl 
//Trace prints the name of the variable and the value.
int dp[N][210], arr[N], n, k, pref[N], p[N][210];
deque<int> st;int ind;
void func(bool a)
{
	if(a==1) return ;
	while(true) {}
}
double inter(int a, int b)
{
	double ret=(dp[a][ind] - dp[b][ind] + 0.0)/(pref[a] - pref[b] + 0.0);
	return ret;
}
void remove()
{
	while(st.size()>=3)
	{
		int i1=st.front(), i2, i3;st.pop_front();i2=st.front();st.pop_front();i3=st.front();
		if(inter(i1, i3)<=inter(i2, i3)) st.push_front(i1);
		else {st.push_front(i2);st.push_front(i1);return;}
	}
}
signed main()
{
	ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
	cin>>n>>k;pref[0]=0;
	if(n==1)
	{
		cout<<0;return 0;
	}
	for(int i=1;i<=n;i++) {cin>>arr[i];pref[i]=arr[i] + pref[i-1];}
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=k;j++) dp[i][j]=0;
	}
	for(int i=1;i<=n;i++)
	{
		dp[i][1]=pref[i]*(pref[n]-pref[i]);
	}
	for(int j=2;j<=k;j++)
	{
		while(!st.empty()) st.pop_front();
		st.push_front(j-1);ind=j-1;
		for(int i=j;i<=n;i++)
		{	
			while(st.size()>1)
			{
				int a=st.front();st.pop_front();int b=st.front();
				if(dp[a][ind] - pref[a]*(pref[n]-pref[i])>dp[b][ind]-pref[b]*(pref[n]-pref[i]))
				{st.push_front(a);break;}
			}
			int opt=st.front();
//			assert(opt>=1);assert(opt<i);
			dp[i][j]=dp[opt][j-1] -pref[opt]*(pref[n]-pref[i]);
			dp[i][j]+=(pref[i])*(pref[n]-pref[i]);p[i][j]=opt;
			st.push_back(i);remove();
		}
	}
	int mi, mval=-inf;
	for(int j=1;j<=n;j++) 
	{
		if(mval<dp[j][k])
		{
			mi=j;mval=dp[j][k];
		}
	}
	cout<<mval<<endl;return 0;
	stack<int> sti;sti.push(mi);
	while(sti.size()<k)
	{
		int cur=p[sti.top()][k-sti.size()+1];sti.push(cur);
	}
	while(!sti.empty()) {cout<<sti.top()<<" ";sti.pop();}
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:85:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(sti.size()<k)
        ~~~~~~~~~~^~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 11
• Subtask 3: 0 / 11
• Subtask 4: 0 / 17
• Subtask 5: 0 / 21
• Subtask 6: 0 / 29