Checking for Pandigital Numbers in JavaScript

In this article, we will learn two approaches to check if a number is pandigital using JavaScript. Pandigital numbers are fascinating because they include each digit at least once within a specific range. Checking if a number is pandigital can be a common problem in programming challenges or number theory explorations. 

What is a Pandigital Number?

A Pandigital number is a number that includes all the digits within a specific range at least once. For example ?

• A 0-9 pandigital number contains each digit from 0 to 9 at least once, regardless of order.
  
• Similarly, a 1-9 pandigital number would contain every digit from 1 to 9 without repetition.

Example of Pandigital Numbers ?

1023456789 (0-9 pandigital)

987654321 (1-9 pandigital)

Using Arrays and Splice

In the first approach, we check if a number is pandigital by using a Legend Array that acts as a checklist. 

Following are the steps to check for pandigital numbers ?

• Legend Array: A legend array is initialized with digits from 0 to 9.
  
• Iterating Through the Number String: Each digit in the input string is checked against the legend.
  
• Removing Found Digits: If a digit exists in the legend, it is removed using a splice.
  
• Checking the Legend: If the legend array is empty after the loop, all digits from 0 to 9 are present.

Example

Below is an example to check for pandigital numbers using arrays and splice ?

const numStr1 = '47458892414';
const numStr2 = '53657687691428890';
const isPandigital = numStr => {
   let legend = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9'];
   for(let i = 0; i < numStr.length; i++){
      if(!legend.includes(numStr[i])){
         continue;
      };
      legend.splice(legend.indexOf(numStr[i]), 1);
   };
   return !legend.length;
};
console.log(isPandigital(numStr1));
console.log(isPandigital(numStr2));

Output

false
true

Using Sets

A more efficient approach is to use a Set, which avoids frequent modifications and ensures uniqueness.

Following are the steps to check for pandigital numbers ?

• Set Initialization: A Set is created to hold unique digits from the input string.
• Comparison: Another Set is created for all digits from 0 to 9.
• Deleting Found Digits: Digits from the input are removed from the Set of all digits.
• Final Check: If the Set of all digits is empty, the number is pandigital.

Example

Below is an example to check for pandigital numbers using sets ?

const isPandigital = numStr => {
   const uniqueDigits = new Set(numStr); // Store unique digits
   const allDigits = new Set('0123456789'); // Set of all digits 0-9
   for (let digit of uniqueDigits) {
      allDigits.delete(digit); // Remove each digit from the set
   }
   return allDigits.size === 0; // Check if all digits are found
};

console.log(isPandigital('47458892414'));
console.log(isPandigital('53657687691428890'));

Output

false
true

Comparison Table

Feature	First Approach	Second Approach
Ease of Understanding	Simple and beginner-friendly	Slightly complex
Performance	Less efficient for large input	More efficient with Set
Memory Usage	Requires maintaining legend	Efficient use of Set