PHP Challenges: Find the single element appears once in an array where every element appears twice except for one

Last update on May 30 2022 11:49:24 (UTC/GMT +8 hours)

PHP Challenges - 1: Exercise-11 with Solution

Write a PHP program to find the single element appears once in an array where every element appears twice except for one.

Input : array(5, 3, 0, 3, 0, 5, 7, 7, 9)

Sample Solution :

PHP Code :

<?php
function single_number($arr)
{
  $result = 0;
  
       for($i=0; $i<sizeof($arr); $i++)
       {
          $result =  $result ^ $arr[$i];   
          
       }
    return $result;
}
$num = array(5, 3, 0, 3, 0, 5, 7, 7, 9);
print_r(single_number($num)."\n")
?>

Sample Output:

Flowchart:

PHP Code Editor:

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Previous: Write a PHP program to find a single element in an array where every element appears three times except for one.
Next: Write a PHP program to add the digits of a positive integer repeatedly until the result has a single digit.

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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