who is left using power

who_is_left.js

function who_is_left(n) {

  var k = 0
  while (Math.pow(2,(k + 1)) < n)  {
      k=k+1

    if (n - (Math.pow(2,(k + 1)))!=0) {
      console.log( (2 * (n - (Math.pow(2, k))) + 1))
    } else {

      console.log( 1)
    }
  }

}

who_is_left_other_method.js

//Copied from 
// https://www.geeksforgeeks.org/puzzle-100-people-in-a-circle-with-gun-puzzle/
var person = 100;
 
// Placeholder array for person
var a = new Array(person);
 
// Assign placeholders from 1 to N (total person)
for (var i = 0; i < person; i++) {
    a[i] = i + 1;
}
 
// Will start the game from 1st person (Which is at
// placeholder 0)
var pos = 0;
 
// Game will be continued till we end up with only one
// person left
while (a.length > 1) {
    // Current person will shoot the person next to
    // him/her. So incrementing the position.
    pos++;
    // As person are standing in circular manner, for
    // person at last place has right neighbour at
    // placeholder 0. So we are taking modulo to make it
    // circular
    pos = pos% (a.length);
    // Killing the person at placeholder 'pos'
    // To do that we simply remove that element
    a.splice(pos,1)
     
    // There is no need to increment the pos again to
    // pass the gun Because by erasing the element at
    // 'pos', now next person will be at 'pos'.
}
 
// Print Person that survive the game
document.write(a[0]);