How to Count of Repeating Digits in a Given Number in PHP ?

Counting the number of repeating digits in a given number is a common task in programming. This can be useful in various scenarios, such as data analysis or validation. In this article, we will explore different approaches to count the repeating digits in a given number using PHP.

Count of Repeating Digits using String Manipulation and Arrays

One way to count repeating digits is by converting the number to a string, splitting it into an array of digits, and then use array_count_values() function to count the occurrences of each digit. Finally, the array_filter() function is used to filter out digits that occur only once, leaving only the repeating digits.

Example: Illustration of counting the number of repeating digits in a given number in PHP using string manipulation and arrays.

PHP

<?php

function countRepeatingDigits($number) {
    // Converting the number into a string
    // and splitting this string into an array of digits
    $digits = str_split((string)$number);

    // Counting the occurrences of each digit
    $counts = array_count_values($digits);

    // Filtering out counts where the digit occurs only once
      // to find the repeating digits only
    $repeatingCounts = array_filter($counts, function($count) {
        return $count > 1;
    });

    return $repeatingCounts;
}

$num = 1234567654321;
$repeatingCounts = countRepeatingDigits($num);

// Iterating through the results and printing them
foreach ($repeatingCounts as $digit => $count) {
    echo "Digit $digit repeats $count times\n";
}

?>

Output

Digit 1 repeats 2 times
Digit 2 repeats 2 times
Digit 3 repeats 2 times
Digit 4 repeats 2 times
Digit 5 repeats 2 times
Digit 6 repeats 2 times

Time Complexity: O(1)

Auxiliary Space: O(1)

Count of Repeating Digits using Arithmetic Operations

Another approach is to use arithmetic operations to extract each digit of the number and count their occurrences. Finally, filter out those digits that occur only once, leaving only the repeating digits.

Example: Illustration of counting the number of repeating digits in a given number in PHP using arithmetic operations.

PHP

<?php

function countRepeatingDigits($number) {
    $counts = [];

    // Loop through each digit in the given number
    while ($number > 0) {
        // Extract the last digit
        $digit = $number % 10;
        // Remove the last digit from the number
        $number = (int)($number / 10);

        // If the digit is not in the counts array
          // initialize its count to 0
        if (!isset($counts[$digit])) {
            $counts[$digit] = 0;
        }
        $counts[$digit]++;
    }

    // Filter out counts where the digit occurs only once
    $repeatingCounts = array_filter($counts, function($count) {
        return $count > 1;
    });

    return $repeatingCounts;
}

$num = 1234567654321;
$repeatingCounts = countRepeatingDigits($num);

foreach ($repeatingCounts as $digit => $count) {
    echo "Digit $digit repeats $count times\n";
}

?>

Output

Digit 1 repeats 2 times
Digit 2 repeats 2 times
Digit 3 repeats 2 times
Digit 4 repeats 2 times
Digit 5 repeats 2 times
Digit 6 repeats 2 times

Time Complexity: O(1)

Auxiliary Space: O(1)