Question

I am trying to do following:

Create 2 unique numbers that are both within a certain range and they are at least n bigger/smaller.

In example:

Range is 0-600
Minimum “difference” is 150

So the generated numbers could be: [2,400],[120,310],[82,530]

But Not [900,400] or [200,220].

Thats what I have so far:

var posYArray   = [];

for(i=0; i < 2; i++){ 

    var posY    = (Math.random() * 200).toFixed();

    if(i < 1){
        posYArray.push(posY);
    }else{

        for(i=0; i < posYArray.length; i++){ 
            if(posY < posYArray[i]+100){
                posYArray.push(posY);
            }else{
                //Restart loop??
            }
        }

    }

}

But this randomly crashes the browser and also I didnt know a good way to restart the loop when the numbers are too close…

Answer 1

You can shift the gap in which not to choose a number, i.e. pick a random number x between 0 and range – gap, than pick first one between 0 and x and the second between x + gap and range. That would be somewhat more efficient.

var range = 600, gap = 150;
var x = Math.floor(Math.random() * (range - gap));
var posX = (Math.random() * (x)).toFixed();
var posY = (Math.random() * (range - x - gap) + x + gap).toFixed();

Works in O(1).