Check Intensity of Shuffle of an Array in JavaScript

An array of numbers is 100% shuffled if no two consecutive numbers appear together in the array (we only consider the ascending order case here). And it is 0% shuffled if pairs are of consecutive numbers.

For an array of length n there will be n-1 pairs of elements (without distorting its order).

We are required to write a JavaScript function that takes in an array of numbers and returns a number between [0, 100] representing the intensity of shuffle in the array

Example

Following is the code −

const arr = [4, 23, 1, 23, 35, 78, 4, 45, 7, 34, 7];
// this function calculates deviation from ascending sort
const shuffleIntensity = arr => {
   let inCorrectPairs = 0;
   if(arr.length <= 1){
      return 0;
   };
   for(let i = 0; i < arr.length - 1; i++){
      if(arr[i] - arr[i+1] <= 0){
         continue;
      };
      inCorrectPairs++;
   };
   return (inCorrectPairs / (arr.length -1)) * 100;
};
console.log(shuffleIntensity(arr));

Output

Following is the output in the console −

40

It means that 40% chunk of this array is shuffled.