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

PHP Basic Algorithm: Exercise-37 with Solution

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
function test($numbers)
{
          $ctr = 0;
            for ($i = 0; $i < sizeof($numbers) - 1; $i++)
            {
                if (($numbers[$i]==5) && ($numbers[$i + 1]==5) || ($numbers[$i + 1]==6)) $ctr++;
            }
            return $ctr;
 }

echo test([5, 5, 2])."\n";
echo test([5, 5, 2, 5, 5])."\n";
echo test([5, 6, 2, 9])."\n";

Sample Output:

1
2
1

Pictorial Presentation:

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

Flowchart:

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

PHP Code Editor:

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Previous: Write a PHP program to create a new string of the characters at indexes 0,1,4,5,8,9 ... from a given string.
Next: Write a PHP program to check if a triple is presents in an array of integers or not. If a value appears three times in a row in an array it is called a triple.

What is the difficulty level of this exercise?

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC