PHP Challenges: Find a single element in an array where every element appears three times except for one
PHP Challenges - 1: Exercise-10 with Solution
Write a PHP program to find a single element in an array where every element appears three times except for one.
Input : array(5, 3, 4, 3, 5, 5, 3)
Explanation :
Sample Solution :
PHP Code :
<?php
function single_number($arr)
{
$ones = 0;
$twos = 0;
$common_one_two = 0;
for($i=0; $i<sizeof($arr); $i++)
{
$twos = $twos | ($ones & $arr[$i]);
$ones = $ones ^ $arr[$i];
$common_one_two = ~($ones & $twos);
$ones &= $common_one_two;
$twos &= $common_one_two;
}
return $ones;
}
$arr1 = array(5, 3, 4, 3, 5, 5, 3);
$arr2 = array(-1, 1, 1, -1, -1, 1, 0);
print_r($arr1);
print_r('Single Number: '.single_number($arr1)."\n");
print_r($arr2);
print_r('Single Number: '.single_number($arr2)."\n");
?>
Sample Output:
Array ( [0] => 5 [1] => 3 [2] => 4 [3] => 3 [4] => 5 [5] => 5 [6] => 3 ) Single Number: 4 Array ( [0] => -1 [1] => 1 [2] => 1 [3] => -1 [4] => -1 [5] => 1 [6] => 0 ) Single Number: 0
Flowchart:
PHP Code Editor:
Contribute your code and comments through Disqus.
Previous: Write a PHP program to find a single number in an array that doesn't occur twice.
Next: Write a PHP program to find the single element appears once in an array where every element appears twice except for one.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
PHP: Tips of the Day
How to Sort Multi-dimensional Array by Value?
Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:
Example:
function sortByOrder($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
- New Content published on w3resource:
- HTML-CSS Practical: Exercises, Practice, Solution
- Java Regular Expression: Exercises, Practice, Solution
- Scala Programming Exercises, Practice, Solution
- Python Itertools exercises
- Python Numpy exercises
- Python GeoPy Package exercises
- Python Pandas exercises
- Python nltk exercises
- Python BeautifulSoup exercises
- Form Template
- Composer - PHP Package Manager
- PHPUnit - PHP Testing
- Laravel - PHP Framework
- Angular - JavaScript Framework
- Vue - JavaScript Framework
- Jest - JavaScript Testing Framework