#include <iostream>
#include <string> 
#include <cmath>
using namespace std;

//global variables
double c0=3,c1=-2,c2=-3.5,c3=0,c4=1;
int ARRAY[20]={	1,2,3,4,5, 
				10, 12, 15, 16,20,
				20, 30, 50, 100, 200,
				213, 456, 1000, 1201, 2000};
								
double log5(double x=125){	
	double y = log(x)/log(5);
	return y;
}


double polynomial(double x){
	double  y = c4*pow(x,4) + c3*pow(x,3) + c2*x*x + c1*x + c0;
	return y; 
}

double radialbase( double, double );



double myfunction(double x1, double x2){
	cout<<"   called myfunction (double,double)\n";
	return 2*x1 - 3*x2;
}
double myfunction(double x1, int x2){
	cout<<"   called myfunction (double,int)\n";
	return 2*x1 - 3*x2;
}
double myfunction(int x1, double x2){
	cout<<"   called myfunction (int,double)\n";
	return 2*x1 - 3*x2;
}
int myfunction(int x1, int x2){
	cout<<"   called myfunction (int,int)\n";
	return 2*x1 - 3*x2;
}


int teststatic (int times){
	static int static_count=0;
	static_count++;
	cout<<"teststatic called with argument="<<times<<". This is call numer "<<static_count<<"\n";
}



void message(int times){
 if (times>0){
  cout<<"    message call t="<<times<<"\n";
  message(times-1);
 }
}

int factorial(int n){
	cout<<"call_f("<<n<<")   ";
	int out;
	if (n<=1) out= 1;
	else out =  n* factorial(n-1);
	cout<<"ret_f("<<n<<")="<<out<<"   ";
	return out;
}


int f1 (int x){
	x = x +1;
	return x;
}
int f2 (int& x){
	x = x +1;
	// if (y<0) return y;
	// x =99;
	return x;
}



int numChars_Rec(char s, string str, int p)
{
	if(p>=str.length()) return 0;
	int local=0;
	if (str[p]==s) local=1;
	return local+ numChars_Rec(s, str, p+1);
}

int numChars_Loop(char s, string str, int p){
	int count=0;
	for (int l=p; l<str.length();l++){
		if (str[l]==s) count++;
	}
	return count;
}


int Fibonacci_Rec (int n){
	if (n<=1) return n;
	return Fibonacci_Rec(n-1) + Fibonacci_Rec(n-2);
}

int Fibonacci_Loop(int n){
	if (n<2) return n;
	int ret,prev1=1,prev2=0;
	for (int l=2;l<=n;l++){
		ret = prev1 + prev2;
		prev2=prev1;
		prev1=ret;
	}	
	return ret;
	
}
int BinarySearch_Rec(int val, int b, int e){
	cout<<"    calling BinarySearch_Rec b="<<b<<" e="<<e<<"...   ";
	if (ARRAY[b]==val) {cout<<"found, position="<<b<<"\n"; return b;}
	if (ARRAY[e]==val) {cout<<"found, position="<<e<<"\n";return e;}
	if (e-b<=1) {cout<<"not found, exiting\n";return -999;}
	int m = (e+b)/2; cout<<"m="<<m<<"  \n";
	if (ARRAY[m]<=val) return BinarySearch_Rec(val,m,e );
	if (ARRAY[m]>val) return BinarySearch_Rec(val,b,m );	
}

int BinarySearch_Loop(int val, int b, int e){
	int m;
	do {
		cout<<"binary search loop b="<<b<<" e="<<e;
		if (ARRAY[b]==val) {cout<<"found, position="<<b<<"\n"; return b;}
		if (ARRAY[e]==val) {cout<<"found, position="<<e<<"\n"; return e;}
		m = (b+e)/2;cout<< "     m="<<m<<"  \n";
		if (ARRAY[m]<=val) b=m;
		if (ARRAY[m]>val) e=m;	
	} while (e-b>1);
	cout<<"not found, exiting\n";
	return -999;	
}





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

int main(){
	double a = log5(25);
	cout << "\n\nCALLING A FUNCTION \n LOG. a="<<a<<"\n";
	a = log5(); cout<< "calling it again with no argument LOG. a="<<a<<"\n";
	a = polynomial (0.5); cout << "\n polynomial (0.5) = "<<a<<endl;
	a = radialbase (0.3, 2); cout << "\n RBF (0.3, 2) = "<<a<<endl;

//	return 0;

// argument by reference
	cout<<"\n\nTESTING ARGUMENT BY REFEENCE\n";
	int v=0, y = f1(v);
	cout<<"f1: v="<<v<<" y="<<y<<endl;
	
	v=0; y=f2(v);
	cout<<"f2: v="<<v<<" y="<<y<<endl;

//	return 0;

// static variable
	cout<<"\n\nTESTING STATIC VARIABLE\n";
	int x = teststatic(10);
	x = teststatic(120);
	x = teststatic(-30);
//	static_count++; // ERROR: not in scope
		
//	return 0;


// overloading
	a = 1; int b=2;

	cout << "\n\n TESTING OVERLOADING FUNCTION\n";
	double c = myfunction(a,b);
	cout << "integers a="<<a<<" b="<<b<<"  value="<<c<<endl;
	double a1 = 1; double b1=2;
	double cc = myfunction(a1,b1);
	cout << "doubles a="<<a1<<" b="<<b1<<"  value="<<cc<<endl;

//	return 0;



//Recursion
	cout<<"\n\n RECURSIVE CALL to function message\n";
	message(5);

//	return 0;	

//Factorial
	cout<<"\n\n RECURSIVE FACTORIAL\n";
	int m1 = factorial(5);
	cout<<"\n factorial of 5 is "<<m1<<endl<<endl;
	int m2 = factorial (7);
	cout <<"\n factorial of 7 is "<<m2<<endl<<endl;		

 //return 0;	
	
//Fiboacci
	cout<<"\n\n FIBONACCI NUMBERS\n";
	for (int t=0; t<=10; t++){
		cout<< "Fibonacci loop ("<<t<<")="<<Fibonacci_Loop(t)<<endl;
	}
	for (int t=0; t<=10; t++){
		cout<< "Fibonacci recursive ("<<t<<")="<<Fibonacci_Rec(t)<<endl;
	}
	
//	return 0;	
		
//characters count
	string mystring= "Virgil Pavlu";
	char c1='i';
	int count_ = numChars_Rec(c1, mystring, 0);
	cout<<"\n\nTESTING CHARACTER COUNT \n string='"<< mystring << "'  char="<< c1 <<"   count="<< count_ << endl;

//	return 0;
	
//*
//binary search	on array ARRAY, which is int[20] global variable
	int val=4,pos;
	cout<<"\n\n BINARY SEARCH\n ARRAY=["; 
	for (int j=0; j<20; j++) cout<<j<<":"<<ARRAY[j]<<"  ";
	cout<<"]\n";
//	pos=BinarySearch_Loop(val, 0, 19);
	pos=BinarySearch_Rec(val, 0, 19);
	cout<<" value="<<val<<" is at position="<<pos<< endl;
//*/
	return 0;
}

double radialbase( double x1, double x2){
	double gamma = 0.5;
	double y = gamma* (x1-x2)*(x1-x2);
	return y;
}