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PHP Challenges: Find majority element in an array

PHP Challenges - 1: Exercise-23 with Solution

Write a PHP program to find majority element in an array.

Input : array(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 6)

Note: The majority element is the element that appears more than n/2 times where n is the number of elements in the array.

Explanation :

PHP: Find majority element in an array

Sample Solution :

PHP Code :

<?php
function majority_element($arr)
 {
        $idx = 0;
        $ctr = 1;
        
        for($i=1; $i<sizeof($arr); $i++)
        {
            if ($arr[$idx] == $arr[$i])
            {
                $ctr += 1;
            }
            else
             {
                $ctr -= 1;
                if ($ctr == 0)
                {
                    $idx = $i;
                    $ctr = 1;
                }
          }   
        }      
    return $arr[$idx];
}
$num1 = array(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 6);
$num2 = array(1,2,3,3,3,3,2,3,5,3,1,3,3,4,6,1,3,3,4,6,6);
print_r(majority_element($num1)."\n");
print_r(majority_element($num2)."\n");
?>

Sample Output: 

5                                                           
3

Flowchart:

PHP Flowchart: Find majority element in an array

PHP Code Editor:

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Previous: Write a PHP program to push all zeros to the end of an array.
Next: Write a PHP program to find the length of the last word in a string.

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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