infoarena

2 1 2
-20 -10 

        ifstream fin("sum2.in");
	fin>>n>>L>>U;
	for(i=1;i<=n;i++)
	{
		fin>>a[i];
		sum[i]=sum[i-1]+a[i];
	}
	fin.close();
	suma=sum[L];
	size=L;
	left=1;
	right=L;
	sol=sum[L];
	while(right<n && left<=right)
	{
		if(size<U)
		{
			done=false;
			while(a[right+1]>=0 && size<U && right<n)
			{
				done=true;
				right++;
				size++;
				suma=suma+a[right];
				if(size<=U && size>=L)
					sol=max(sol,suma);
			}
			if(done==false)
			{
				right++;
				size++;
				suma=suma+a[right];
				if(size<=U && size>=L)
					sol=max(sol,suma);
			}
		}
		if(size>L)
		{
			done=false;
			while(a[left]<=0 && size>L)
			{
				done=true;
				size--;
				suma=suma-a[left];
				left++;
				if(size<=U && size>=L)
					sol=max(sol,suma);
			}
			if(done==false)
			{
				size--;
				suma=suma-a[left];
				left++;
				if(size<=U && size>=L)
					sol=max(sol,suma);
			}
		}
	}
	ofstream fout("sum2.out");
	fout<<sol<<"\n";
	fout.close();
	return 0;

#include<iostream>
#include<fstream>
#define N 100004

using namespace std;

ifstream in("sum2.in");
ofstream out("sum2.out");

int n,l,U,smax=-1000000,d[N],p=1,u,y[N];
short x[N];

inline void swap(int &a, int & b) {
	int t=a;
	a=b;
	b=t;
}

inline void add(const int &a) {
	d[++u]=a;
}

inline void stanga(int i) {
	if(p<=u && i - d[p]>= U)
		++p;
}

inline void dreapta() {
	while(u!=p && y[d[u]] <= y[d[u-1]]) {
		swap(d[u],d[u-1]);
		--u;
	}
}

void so() {
	int i;
	
	for(i=0;i<U-l-1;++i) {
		add(i);
		dreapta();
	}
	
	for(i=U;i<=n;++i) {
		stanga(i);
		add(i-l-1);
		dreapta();
		if(y[i]-y[d[p]]>smax)
			smax=y[i]-y[d[p]];
	}
	add(i-l-1);
	dreapta();
	if(y[i-1]-y[d[p]]>smax)
		smax=y[i-1]-y[d[p]];
}

int main() {
	int i;
	in >> n >> l >> U;
	
	for(i=1;i<=n;++i) {
		in >> x[i];
		y[i]=x[i] + y[i-1];
	}
	
	so();
	
	out << smax;
	
	return 0;
}

2 1 2
1000 -1000

3 1 3
1000 1000 -1000

9 2 3
100 100 -1000 10 -15 100 100 -15 1

5 2 4
-1000 -1000 -1000 1000 1000