Question

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Generate unique number within range (0 – X), keeping a history to prevent duplicates

Writing a function that make random array,as I wrote below:

RandomArray(10)

=> [0,2,3,9,6,5,4,7,8,1]

🙁

I’m not learning progarming when school days so i wrote a ugly one.Here is my program.

var min = 0,
    max = 15,  //Here generate an random array from 0-14
    i,
    j,
    arr = [],
    temp = [];

for (i = min;i<max; i++){
    arr.push(i);
}

for(j=min;j<1000;j++){
   temp.push(arr[Math.floor(Math.random() * arr.length)]);  
}
function unique(array){
      var b = [];
      for(var i=0; i<array.length; i++){
         if(b.indexOf(array[i]) == -1) b.push(array[i]);
      }
      return b;
}
alert(unique(temp));

I wrote this program by searching the internet,it’s not perfect i think, there is no arithmetic in it…

Answer 1

function randomArray(n) {

  var array = [];
  for (i = 0; i < n; i++) {
    array[i] = i;
  }
  var newArray = [];
  for (i = 0; i < n; i++) {
    var num = Math.round(Math.random() * (n - i - 1));
    newArray[i] = array[num];
    array.splice(num, 1);
  }
  alert(newArray);
}
randomArray(100);