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 13:05:18 (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:

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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