I need to generate random numbers from 3 to 10 in a matrix of 8x8 without repeating them and since the matrix is something big the other numbers should be placed in 0
an example
{0,0,0,0,0,6,0,0}
{0,0,3,0,0,0,0,0}
{0,0,0,0,0,0,0,9}
{0,0,0,4,0,0,0,0}
{0,0,0,0,0,0,7,0}
{0,0,5,0,0,0,0,0}
{0,0,0,0,0,8,0,0},
{10,0,0,0,0,0,0,0}
We are going to turn the problem around. As I see it, you do not need random numbers from 3 to 10. You ALWAYS need that sequence of numbers, but placed randomly within the 8x8 matrix.
What I would do, then, is a cycle that gives me the sequence of numbers from 3 to 10, and for each one, I generate a random position and, if it is not already occupied by another number, I assign it the value of the sequence. If you are already busy, I repeat the process until I find one that is not.
In code, it would be something like:
public static void main (String args[]) {
int FILAS = 8;
int COLUMNAS = 8;
int[][] matriz = new int[FILAS][COLUMNAS];
Random aleatorio = new Random();
boolean asignado;
for (int i = 3; i != 10; i++) {
asignado = false;
do {
int fila = aleatorio.nextInt(FILAS);
int columna = aleatorio.nextInt(COLUMNAS);
if (matriz[fila][columna] == 0) {
matriz[fila][columna] = i;
asignado = true;
}
} while (!asignado);
}
for (int i = 0; i < FILAS; i++) {
for (int j = 0; j < COLUMNAS; j++) {
System.out.print(matriz[i][j] + ", ");
}
System.out.print("\n");
}
}
What it produces for me, for example, is exit:
0, 9, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 4, 0, 0, 0, 0, 0, 0,
0, 5, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 7,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 3, 0, 0,
6, 0, 0, 8, 0, 0, 0, 0,
To generate the random numbers you can use java.util.Random
This code stores the 8 random numbers in a vector. From there you can place them in the matrix applying your own criteria.
int [] aleatorios = new int[8];
Random random = new Random();
for(int i=0;i<8;i++){
aleatorios[i] = random.nextInt(8) + 3;
}