PHP Exercises: Count the number of two 5's are next to each other in an array of integers

Last update on May 28 2025 13:07:49 (UTC/GMT +8 hours)

37. Count Adjacent 5's with 6 Variation

Write a PHP program to count the number of two 5's are next to each other in an array of integers. Also count the situation where the second 5 is actually a 6.

Sample Solution:

PHP Code :

<?php
// Define a function that counts the occurrences of specific patterns in an array
function test($numbers)
{
    // Initialize a counter variable
    $ctr = 0;

    // Iterate through the array up to the second-to-last element
    for ($i = 0; $i < sizeof($numbers) - 1; $i++)
    {
        // Check if the current and next elements form a specific pattern
        if (($numbers[$i] == 5) && ($numbers[$i + 1] == 5) || ($numbers[$i + 1] == 6))
        {
            // Increment the counter if the pattern is found
            $ctr++;
        }
    }

    // Return the final count
    return $ctr;
}

// Test the function with different arrays
echo test([5, 5, 2])."\n";
echo test([5, 5, 2, 5, 5])."\n";
echo test([5, 6, 2, 9])."\n";
?>

Explanation:

Function Definition:

The test function takes an array of numbers, $numbers, as input and counts occurrences of specific patterns.

Initialize Counter:

A variable $ctr is initialized to 0 to keep track of the pattern matches found.

Loop through the Array:

A for loop iterates through $numbers from the start to the second-to-last element, using sizeof($numbers) - 1 as the limit.

Pattern Check:

The if condition checks if the current element ($numbers[$i]) is 5 and the next element ($numbers[$i + 1]) is either:

5 (two consecutive 5’s) or
6 (5 followed by 6).

If either pattern is found, $ctr is incremented by 1.

Return the Result:

After the loop completes, the function returns the final count of pattern occurrences stored in $ctr.

Output:

1
2
1

Visual Presentation:

PHP Basic Algorithm Exercises: Count the number of two 5's are next to each other in an array of integers

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to count pairs of adjacent 5's in an array, also counting a 5 followed by 6 as a valid pair.
Write a PHP function to iterate through an array and tally adjacent occurrences of the number 5, allowing for a trailing 6.
Write a PHP program to scan an integer array and detect consecutive number patterns where 5 can be followed by either 5 or 6.
Write a PHP script to check every pair of adjacent numbers in an array and count them if they meet the criteria for 5 and alternate 6.

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