PROBLEMA 1.

import java.io.*;
import java.util.*;
class problmeaUnu{
	public static void main(String args[]){
		int contor=0;
		try{
			//FileReader fr=new FileReader("raport.txt");
			DataInputStream read = new DataInputStream(new FileInputStream("binar.bin")); //nebunia care ma ajuta sa citesc chestii
			for(;;) {
				int numar;
				try{
					numar = read.readInt(); //citeste numar intreg
					System.out.println(numar);
					if(NumarPrim(numar) == 1) contor++; //daca e prin crestem contor
				}
				catch(EOFException ignored){
					//a dat de capatul fisierului
					break; //opreste citire
				}
			}
			System.out.println("Numar elemente prime: " + contor);
		}
		catch(IOException e){
			e.printStackTrace();
			System.exit(1);
		}
	}

	public static int NumarPrim(int n)
	{
		int presupunem_prim = 1;
		for(int i = 2; i < n/2; i++)
		{
			if(n%i == 0) //se imparte -> nu e numar prim!
			{
				presupunem_prim = 0;
			}
		}
		return presupunem_prim;
	}
}
PROBLEMA 2.

import java.io.*;
import java.util.*;
class problmeaUnu{
	public static void main(String args[]){
		int contor=0;
		Scanner sc = new Scanner(System.in);
		System.out.println("Introduceti numarul: ");
		String sir_citit = sc.next();//citire sir de la tastatura
		int numar = Integer.parseInt(sir_citit);//convertire sir la intreg
		try{
			//FileReader fr=new FileReader("raport.txt");
			File file = new File("fisier.txt");
  			BufferedReader br = new BufferedReader(new FileReader(file));
  			String st;
			for(;;) {
				st = br.readLine();
				if(st == null) break;
				//System.out.println(st);
				if(numar == st.length()) //N de la tastatura == lungimea sirului citit din fisier
					contor++;
			}
			System.out.println("Numarul liniilor de lungime egala cu " + numar + " este: " + contor);
		}
		catch(IOException e){
			e.printStackTrace();
			System.exit(1);
		}
	}

PROBLEMA 3.

import java.io.*;
import java.util.*;
class problmeaUnu{
	public static void main(String args[]){
		ArrayList<Integer> array = new ArrayList<Integer>();
		Scanner sc = new Scanner(System.in);
		for(;;)
		{
			System.out.println("Introduceti numar: ");
			String cuvant = sc.next(); //citesc numar de la tastatura ca sir de caractere
			int numar = Integer.parseInt(cuvant); //convertire la intreg
			if(numar == -1) break; //oprire daca a citit -1
			array.add(numar); //adauga cuvant in array (vector de numere)
		}
		int suma = 0;
		for(int i = 0; i < array.size(); i++)
		{
			suma = suma + array.get(i);
		}
		float medie = suma/array.size(); //suma/nr numere
		System.out.println("Media aritmetica este: " + medie);
	}
}

PROBLEMA 4.

import java.io.*;
import java.util.*;
class problmeaUnu{
	public static void main(String args[]){
		ArrayList<String> array = new ArrayList<String>();
		Scanner sc = new Scanner(System.in);
		for(;;)
		{
			System.out.println("Introduceti sir: ");
			String cuvant = sc.next(); //citeste cuvant
			if(cuvant.equals("stop")) break; //oprire daca a citit stop
			array.add(cuvant); //adauga cuvant in array (vector de cuvinte)
		}
		int diferite = 1; //presupunem ca sunt diferite(1)
		for(int i = 0; i < array.size(); i++)
		{
			for(int j = i+1; j < array.size(); j++)
			{
				if(array.get(i).equals(array.get(j))) //cuvintele sunt identice
				{
					diferite = 0; //nu sunt diferite
				}
			}
		}
		if(diferite == 0) System.out.println("Cuvintele nu sunt diferite");
			else System.out.println("Cuvintele sunt diferite");
	}

}