output "No solution" when there is no ans.
Enlarge the size of the two arrays to more than 10^5!




// This is your code. (corrected)
Source

Problem Id:2620  User Id:others_code 
Memory:980K  Time:107MS
Language:C++  Result:Accepted

Source 

#include<iostream>

using namespace std;

///////////////////////////////////////
template<class T>
void Swap(T &x, T &y)
{
	T temp;
	temp = x;
	x    = y;
	y    = temp;
}


template <class T>
int Partition(T a[], int p, int t)
{
	int i=p;
	int	j=t+1;
	T	x=a[p];
	while(1)
	{
		while(a[++i].L<x.L);
		while(a[--j].L>x.L);
		if(i>=j) break;
		Swap(a[i], a[j]);
	}
	a[p]=a[j];
	a[j]=x;
	return j;
}

template <class T>
void QuickSort(T a[], int p, int t)
{
	if(p<t)
	{
		int q = Partition(a,p,t);
		QuickSort(a, p, q-1);
		QuickSort(a, q+1, t);
	}
}


////////////////////////////////////////////

typedef struct node
{
	long L;
	long R;
}node;


long i,j,k,m,a,b,n,count,flag,tag;
bool s[100005];


int main()
{
	node n[100005];
	cin>>m;
	k=0;
	tag=1;
	scanf("%ld%ld", &a,&b);
	while(a!=0 || b!=0)
	{
		n[k].L=a;
		n[k].R=b;
		if(a<=0 && b>=m) {tag=0; j=k;}
		k++;
		scanf("%ld%ld", &a,&b);
	}

	count = 0;
	if(!tag) cout<<1<<endl<<n[j].L<<' '<<n[j].R<<endl;
	else
	{
		flag = 0;
		QuickSort(n, 0, k-1);      
		for(i=0; i<k; i++) s[i]=0;
		a=0;
		b=0;
		
		for(i=0; i<k; i++)
		{	if(n[i].L>a) break;
			else 
			{
				
				while(n[i].L<=a && i<k)
				{
					if(n[i].R>b)
					{b = n[i].R; j=i;}
					i++;
				}
				a=b;
				s[j]=1;
				count++;
				if(b>=m) {flag=1; break;}
				i--;
			}
		}
	
		if(!flag) cout<<"No solution"<<endl; 
		else 
		{
			cout<<count<<endl;
			for(j=0;j<k; j++)
				if(s[j])
					cout<<n[j].L<<' '<<n[j].R<<endl;
		}
	}
     
	
	return 1;
}