Examen JAVA 2017

// ex2

import java.util.Vector;

// nbr impair = 2k + 1
public class UtilTab{
    public static int[] genere(int n) {
        int T[] = new int[n];
        for(int i=0; i<n; i++)
            T[i] = 2 * i + 1;
        return T;
    }

    public static int[] somme(Vector<Integer> a, Vector<Integer> b) // l correction dylhom dayrin tableau 3adi xDD
    {
        if(a.size() != b.size())
            return null;

        int T[] = new int[a.size()];

        for( int i=0 ; i<a.size() ; i++ )
            T[i] = a.get(i) + b.get(i);

        return T;
    }

    public static void main (String args[]){
        int T[] = genere(1);
        for( int i=0 ; i<T.length ; i++ )
            System.out.print(T[i]+" ");

        Vector<Integer> a = new Vector<Integer>();
        a.add(2);
        a.add(4);
        a.add(6);

        Vector<Integer> b = new Vector<Integer>();
        b.add(1);
        b.add(3);
        b.add(5);

        try {
            int Tf[] = somme(a, b); // peut retourner null
            System.out.println("");
            for( int i=0 ; i<Tf.length ; i++ )
                System.out.print(Tf[i]+" ");
        } catch (Exception e){
            System.out.println("Tailles différents!");
        }
    }
}

// ex3

public static void main (String args[]){
    int p[] = {1, 7, 0, 4};
    System.out.println("Dérivé :");
    for( int i=p.length-1 ; i>0 ; i-- ) {
        int coeff = i*p[i]; //l puissance * coefficient
        if(coeff != 0) { // ila kan = 0, dont print
            System.out.print(coeff);
            int deg = i-1; // as you know, (x^2)' = 2*(x^2-1) ==> (x^i)' = i*x^(i-1)
            if(deg != 0) // ila kan deg = 0, dont print x^0, = 1, so no x should be printed
            System.out.print("x^"+deg);
            if(i>1)
                System.out.print("+");
        }
    }
}

// ex4

public static void main (String args[]){
    String str = "Laval";
    int i, j;
    for( i=0, j=str.length()-1 ; i<j ; i++, j-- )
        if( str.toLowerCase().charAt(i) != str.toLowerCase().charAt(j) )
            break;

    System.out.print( i<j ? "Faux" : "Vrai");
}

// ex5
public static void main(String[] args) {
        String str = "Bonjour";
        String subStr = "jou";
        boolean flag = true;

        if( str.length() < subStr.length() )
            flag = false;

        if( flag ){
            int i, j;
            for( i=0, j=0 ; i<str.length() && j!=subStr.length() ; i++ )
            {
                if( str.charAt(i) == subStr.charAt(j) )
                    j++;
                else
                    j=0;
            }
            flag = j==subStr.length(); // true ila ga3 les chars dyl subStr kinin f str (\j++)
        }

        System.out.println( flag ? "Vrai" : "Faux" );
}