# include <iostream>
// #include <string> 
// #include <cmath>
// #include <cstdlib>
// #include <iomanip>
// #include <fstream>
#include <vector>

using namespace std;

const int MAXHASH = 100000;




//a simple hash function from words to integers (0, MAXHASH)
int myhash_function(char s[]){
	int sum=0,i=0,v;
	cout<<"\n hash("<<s<<"):\n";
	while(s[i]>0){
		i++;
		v = s[i] * i*i;
		sum += v;
		cout << "        "<< i <<"  "<< s[i-1]<<"  "<<v<<"   "<< sum<< endl;
	}
	int sumret  = sum % MAXHASH;
	cout <<sum<<" % "<< MAXHASH << " = "<<sumret <<endl<<endl;
	return sumret;
}


void displayVector(vector<int> v,char message[]){
	cout<<message<<" ";
	for (int i=0;i<v.size();i++) {
			cout<< "\n "<<i<<":"<<v[i];
			cout<<" adress="<< &v[i];
	}
	cout <<"\n vector_size="<<v.size();
}
void displayArray(int X[], int array_size, char message[]){
	cout<<message<<" ";
	
	for (int t=0;t<array_size;t++) cout <<t<<":"<<X[t]<<" ";
//	cout<<"\n";
}

//int changeArray(const int X[], int array_size){
int changeArray(int X[], int array_size){
	int local_array_size = sizeof(X)/sizeof(int);// gets the wrong size
	cout<<" \n   local size (wrong?)="<<local_array_size<<endl;
	for (int t=0;t<array_size; t++) X[t]++;
}





//////////////////////////////////////////////
int Partition(int A[], int b, int e)
{
	cout << " \n\n Partition function not completed !!\n\n"; 
	return 0; //fill up this function
}


void QuickSort(int A[], int b, int e){
	static int first_size = e-b+1;
	cout<<"    QuickSort called b="<<b<<" e="<<e<<" ... ";
	
	int q = Partition(A,b,e);
	displayArray(A, first_size," PARTITION: ");
	cout<<" pivot_index="<<q;  cout<<endl;
//	cin.get();
	if (b<q-1) QuickSort(A,b,q-1);
	if (q+1<e) QuickSort(A,q+1,e);
	
	
}


///////////////////////////////////////////////////
int main(){

//declaring array, size, access elements
	int A[10];
	int mem_size = sizeof (A);
	cout<< "\n\nARRAYS\n A is an array on "<< mem_size<< " bytes\n";
	int A_size = sizeof (A)/sizeof(int);
	cout<<"number of elements in A is "<<A_size<<endl;
	//return 0;
	
//printing array
	A[1] = 2; A[4]=-5; A[8]=1023;
	cout<<"\ndisplaying array A first time";
	for (int i=0;i<A_size;i++){
		cout<< "\n A["<<i<<"]="<<A[i];
		cout<<" adress of A["<<i<<"]="<< &A[i];
	}
//	cout <<endl;	
//	return 0;

//write out of bounds	
//input array is a reference variable
	changeArray(A, A_size);
	displayArray(A, A_size, "\n displaying A second time: ");
//	return 0;	
	
	int next_var=1;	
	cout<<"\n next_var="<<next_var<<" address="<<&next_var;
	int ind ; 
	ind =  (&next_var -&A[10])  + A_size; //figure out a fictive index such that A[ind] has the address of next_var
//	cout<<"\nind="<<ind<<"\n";	
	A[ind]=-999;
	cout<<"\n ind="<<ind<<"\n next_var="<<next_var<<" address="<<&next_var;
	cout <<endl;	




//	return 0;

//quicksort		
	int A2[]={10, 13, 15, 20, -1, -34, 24, -53, 10};
	// int A2_size = sizeof(A2)/sizeof(int);
	// displayArray(A2, A2_size, "\nA2 before quicksort");cout<<endl;
	// QuickSort(A2,0,A2_size-1);
	// displayArray(A2, A2_size, "\nA2 after quicksort");cout<<endl;


	
	
	
//copy array	
	int A3[10];
//	A3=A; //error
	int A3_size = sizeof(A3)/sizeof(int);
	for (int i=0;i<10;i++) A3[i]=A[i];
	displayArray(A3, A3_size, "\nA3 after copying A into A3 : \n");cout<<endl;
	
//	return 0;
//matrix
	int M[2][5]={0,1,2,3,4,
				 -10, -11, -12, -13, -14};
	int M_size= sizeof(M)/sizeof(int);
	cout<< "\n\nARRAYS 2 DIM\n M is an array on "<< sizeof(M)<< " bytes\n";
	cout<<"number of elements in M is "<<M_size<<endl;
	for (int i=0;i<2;i++){
		for (int j=0;j<5;j++){
			cout<< "\n M["<<i<<"]"<<"["<<j<<"]="<<M[i][j];
			cout<<" adress of M["<<i<<"]"<<"["<<j<<"]="<< &M[i][j];
		}
	}
	cout<< "\n\n M[2]="<<M[2]<<endl;
	cout<<" adress of M["<<2<<"]"<<"["<<0<<"]="<< &M[6][0];
 
//intro to pointers	
	int z;
	z = *((int*)M+6);
	cout <<"\n\nz="<<z<<endl;
//	return 0;


//vectors
	vector<int> n(10,-1);
	displayVector(n,"\n\n displaying vector n: ");

	 n[14]=-41;	
	 displayVector(n,"\n\n displaying vector n after n[14]: ");
	
	n.push_back(21);
	displayVector(n,"\n\n displaying vector n after push_back: ");

	n[2]=0; n[3]=11; n[7]=9; n[0]=45; n[5]=5; n[1]=100;
	displayVector(n,"\n\n displaying vector n after assignments: ");
	
//	return 0;
	int nlast;
	n.pop_back();
	displayVector(n,"\n\n displaying vector n after pop_back: ");
	cout <<" nlast="<<nlast;
	n.pop_back();
	displayVector(n,"\n\n displaying vector n after seconfd pop_back: ");
	
	n.resize(3,-999);
	displayVector(n,"\n\n displaying vector n after resize: ");
		
	 n.clear();
	 displayVector(n,"\n\n displaying vector n after clear: ");
	cout<<endl;

//	return 0;

//simple hashing
	char s1[]="Northeastern University";
	int h1 = myhash_function(s1);

//return 0;	

	char s2[]="Virgil"; int h2 = myhash_function(s2);
//return 0;	

	char s3[]="Wonderland"; int h3 = myhash_function(s3);
//return 0;	

	char s4[]="Alice in Wonderland"; int h4 = myhash_function(s4);

	char s5[]="The quick brown fox jumps over the lazy dog"; int h5 = myhash_function(s5);
	
	



	
	
	return 0;
		
}