Populate vector and check if current position value is equal to previous

Question

btnInnerText(btns[0],sorteio());
var bool = true;
for(var i=1;i<btns.length;i++){
    do{
        btnInnerText(btns[i],sorteio());
        for(var j=0;j<btns.length;j++){
            if(getValorBTN(i)==getValorBTN(j))
                bool=false;             
            else
                bool=true;

        }
    }while(bool==true)

}

for(var i=0;i<btns.length;i++){
    console.log("Posição = "+i+" - Valor = "+getValorBTN(i));
}

The problem is that it always generates some repeated numbers. And what I want is that Randomize random numbers without repeating any value in the vector

The draw function is to draw a number between 1 and 10 and the function getValorBTN is to take the values of the HTML boats

function getValorBTN(posicaoBTN){
    var valor=parseInt(document.getElementById(btns[posicaoBTN]).textContent);
    return valor;
}

Another thing I don’t quite understand is that if I put the condition while(bool==false) gets into loop infinity. I’m certainly confusing things, but I think it was to repeat when bool=false and leave when it’s the other way around.

Answer 1

i want Randomize random numbers without repeating any value in the vector

First, let’s create a function that returns a random number within a specific range.

function obterNumeroAleatorio(minimo, maximo) {
  return minimo + Math.floor(Math.random() * (maximo - minimo + 1));
}

Now, let’s create a function that accumulates N random numbers within a specific range.

function gerarNumerosSemRepeticao(quantidadeNumeros, minimo, maximo) {
  const numerosSemRepeticao = new Set();

  while (numerosSemRepeticao.size < quantidadeNumeros) {
    const numeroAleatorio = obterNumeroAleatorio(minimo, maximo);
    numerosSemRepeticao.add(numeroAleatorio);
  }

  return [...numerosSemRepeticao];
}

Therefore, to generate 10 random numbers between 1 and 100, just call

const numeros = gerarNumerosSemRepeticao(10, 1, 100);
console.log(numeros);

• In case you don’t know what it is Set, click here.
• In case you don’t know what it is [...x], click here.

---

If you want to use arrays only, you just make a loop for comparing the number drawn with each of the numbers already selected.

function gerarNumerosSemRepeticao(quantidadeNumeros, minimo, maximo) {
  const numerosSelecionados = [];

  while (numerosSelecionados.length < quantidadeNumeros) {
    const numeroSorteado = obterNumeroAleatorio(minimo, maximo);
    let encontrouIgual = false;

    for (const numero of numerosSelecionados) {
      if (numero === numeroSorteado) {
        encontrouIgual = true;
        break;
      }
    }

    if (!encontrouIgual) {
      numerosSelecionados.push(numeroSorteado);
    }
  }

  return numerosSelecionados;
}

But keep in mind that this greatly worsens the execution time of the function. Using Set she is O(n), using array she becomes O(n^2). If you don’t know what that means, click here.

---

Just out of curiosity, know that you can also create an array of sequential numbers and mix them randomly. The final result will be the same (whereas the random number range comprises all numbers in the vector).

To mix the elements of a vector use Knuth’s shuffle algorithm (if you don’t know what it is, click here).

function misturarElementos(vetor) {
  function inverter(i, j) {
    const temp = vetor[i];
    vetor[i] = vetor[j];
    vetor[j] = temp;
  }

  for (let i = vetor.length - 1; i; i--) {
    let j = obterNumeroAleatorio(0, i);
    inverter(i, j);
  }
}

Example of use:

const numeros = [];

// Preencher o vetor com números sequenciais
for (let i = 1; i <= 10; i++) {
  numeros.push(i);
}

// Usar o Knuth shuffle para embaralhar os elementos no vetor
misturarElementos(numeros);

// Agora os elementos parecem aleatórios!
console.log(numeros);

This algorithm is O(n).