javascript - Most efficient method to check for range of numbers within number without duplicates

Question

Given a number n , a minimum number min , a maximum number max , what is the most efficient method to determine

1. Number n is or is not within range , inclusive of , min - max

2. Number n does or does not contain duplicate numbers

3. Efficiency meaning here that the method or set of methods requires the least amount of computational resources and returns either true or false in the least amount of time

4. Context: Condition at if within a for loop which could require from thousands to hundreds of thousands of iterations to return a result; where milliseconds required to return true or false as to Number check could affect performance

At Profiles panel at DevTools on a collection of 71,3307 items iterated, RegExp below was listed as using 27.2ms of total 1097.3ms to complete loop . At a collection of 836,7628 items iterated RegExp below used 193.5ms within total of 11285.3ms .

Requirement: Most efficient method to return Boolean true or false given above parameters , within the least amount of time.

Note: Solution does not have to be limited to RegExp ; used below as the pattern returned expected results.

---

Current js utilizing RegExp re , RegExp.protype.test()

var min = 2
, max = 7
, re = new RegExp("[" + min + "-" + max + "](.)(?!=1)", "g")
, arr = [81, 35, 22, 45, 49];

for (var i = 0; i < arr.length; i++) {
  console.log(re.test(arr[i]), i, arr[i])
    /*
      false 0 81 
      true 1 35
      false 2 22
      true 3 45
      false 4 49 
    */
}

Answer 1

Associative arrays approach:

This has the advantage of being easily understandable.

function checkDigits(min, max, n) {
    var digits = Array(10);                   // Declare the length of the array (the 10 digits) to avoid any further memory allocation
    while (n) {
        d = (n % 10);                         // Get last digit
        n = n / 10 >>0;                       // Remove it from our number (the >>0 bit is equivalent to compose(Math.floor, Math.abs))
        if (d < min || d > max || digits[d])  // Test if "d" is outside the range or if it has been checked in the "digits" array
            return false;
        else
            digits[d] = true;                 // Mark the digit as existing
    }
}

var min = 2
, max = 7
, arr = [81, 35, 22, 45, 49];

function checkDigits(min, max, n) {
    var digits = Array(10);                   // Declare the length of the array (the 10 digits) to avoid any further memory allocation
    while (n) {
        d = (n % 10);                         // Get last digit
        n = n / 10 >>0;                       // Remove it from our number (the >>0 bit is equivalent to compose(Math.floor, Math.abs))
        if (d < min || d > max || digits[d])  // Test if "d" is outside the range or if it has been checked in the "digits" array
            return false;
        else
            digits[d] = true;                 // Mark the digit as existing
    }
    return true;
}

for (var i = 0; i < arr.length; i++) {
  console.log(checkDigits(min, max, arr[i]), i, arr[i])
}