Make array consecutive

i got stucked in a chalenge in codeFights.my code pass the simple test and fail in just 2 from five of hidden tests her is the chalenge instruction:

Ratiorg got statues of different sizes as a present from CodeMaster for his birthday, each statue having an non-negative integer size. Since he likes to make things perfect, he wants to arrange them from smallest to largest so that each statue will be bigger than the previous one exactly by 1. He may need some additional statues to be able to accomplish that. Help him figure out the minimum number of additional statues needed.

Example

For statues = [6, 2, 3, 8], the output should be
makeArrayConsecutive2(statues) = 3.

Ratiorg needs statues of sizes 4, 5 and 7.

Input/Output

[time limit] 4000ms (js)
[input] array.integer statues

An array of distinct non-negative integers.

Constraints:
1 ≤ statues.length ≤ 10,
0 ≤ statues[i] ≤ 20.

[output] integer

The minimal number of statues that need to be added to existing statues such that it contains every integer size from an interval [L, R] (for some L, R) and no other sizes.

and here is my code :

function makeArrayConsecutive2(statues) {
 //range the table from min to max
 var rang=statues.sort();
 var some=0;
 //if the table is one element
 if(rang.length-1==0){
  return 0;

 }else{
  //if the table contain more then one element
  for(i=0;i<=rang.length-2;i++){
   //add the deference of two consecutive position -1 
   //to find the number of missing numbers
   some+=(rang[i+1]-rang[i]-1);
 }
  return some;
 }
}

Solution 1:

Everything is correct, except the sorting part.

You have used sort function to sort the array in increasing order

var rang = statues.sort();

But if sort function is not provided a compare function, it converts its elements in strings and then sort it in unicode order.

For eg: [2,1,11] will be sorted as [1,11,2] which will give undesired output.

Correct way is

var rang = statues.sort(function (a, b){
    return (a - b) 
});

Solution 2:

SO THE LOGIC TO SOLVE THIS QUESTION IS:

1. Find the Smallest and Largest Element in Array.

2. Get the count of can say, difference of Largest and Smallest value of array in order to calculate, how many elements must be there to make it as a continuous array . Like from 5 to 9, count of total elements must be 5 ( i.e.5,6,7,8,9) and also add 1 to the result to make count inclusive.

3. Find the Length of the Array

4. Subtract the count i.e. "difference of largest and smallest value " with the length of array

PYTHON CODE (For explanation):

def makeArrayConsecutive2(statues):
    max_height = max(statues)
    min_height = min(statues)
    array_length  = len(statues)

    count_of_element = max_height - min_height + 1
    # '1 ' is added to make it inclusive
  
    return count_of_element-array_length

and Python one liner :

def makeArrayConsecutive2(statues):
    return max(statues)-min(statues)-len(statues)+1