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Digit Difference Sort

Description

Given an array of integers, sort its elements by the difference of their largest and smallest digits. In the case of a tie, that with the larger index in the array should come first.

Example

For a = [152, 23, 7, 887, 243], the output should be digitDifferenceSort(a) = [7, 887, 23, 243, 152].

Here are the differences of all the numbers:

  • 152: difference = 5 - 1 = 4;
  • 23: difference = 3 - 2 = 1;
  • 7: difference = 7 - 7 = 0;
  • 887: difference = 8 - 7 = 1;
  • 243: difference = 4 - 2 = 2.

23 and 887 have the same difference, but 887 goes after 23 in a, so in the sorted array it comes first.

Input/Output

  • [execution time limit] 4 seconds (js)

  • [input] array.integer a

    An array of integers.

    Guaranteed constraints:
    0 ≤ sequence.length ≤ 104,
    1 ≤ sequence[i] ≤ 105.

  • [output] array.integer

    • Array a sorted as described above.

[JavaScript (ES6)] Syntax Tips

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// Prints help message to the console
// Returns a string
function helloWorld(name) {
console.log("This prints to the console when you Run Tests");
return "Hello, " + name;
}

Solution

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a = [152, 23, 7, 887, 243];
function digitDifferenceSort(a) {
  var positioned = a.map((n, i) => ({ n, i }));
  return positioned
    .sort(function (b, c) {
      var bDigits = String(b.n).split("").map(Number);
      var cDigits = String(c.n).split("").map(Number);
      var val1 = Math.max(...bDigits) - Math.min(...bDigits);
      var val2 = Math.max(...cDigits) - Math.min(...cDigits);
      return val1 !== val2 ? val1 - val2 : c.i - b.i;
    })
    .map((el) => el.n);
}