PHP Challenges: Find a single number in a array that doesn't occur twice

PHP Challenges - 1: Exercise-9 with Solution

Write a PHP program to find a single number in an array that doesn't occur twice.

Input : array(5, 3, 4, 3, 4)

Explanation :

Sample Solution :

PHP Code :

<?php
// Function to find the single number in an array
function single_number($arr)
{
    // Initialize $result with the first element of the array
    $result = $arr[0];

    // Iterate through the array starting from the second element
    for ($i = 1; $i < sizeof($arr); $i++)
    {
        // Use bitwise XOR operation to find the single number
        $result = $result ^ $arr[$i];
    }
    
    // Return the single number found
    return $result;
}

// Define two arrays
$arr1 = array(5, 3, 4, 3, 4);
$arr2 = array(3, 2, 5, 2, 1, 5, 3);

// Print the first array
print_r($arr1);
// Print the single number found in the first array
print_r('Single Number: ' . single_number($arr1) . "\n");

// Print the second array
print_r($arr2);
// Print the single number found in the second array
print_r('Single Number: ' . single_number($arr2) . "\n");
?>

Explanation:

Here is a brief explanation of the above PHP code:

• The code defines a function named "single_number()" which finds the single number in an array where every element appears twice except for one. It takes an array '$arr' as input.
• Inside the function:
• It initializes '$result' with the first element of the array.
• It iterates through the array starting with the second element.
• Within each iteration, it uses the bitwise XOR (^) operation to find the single number.
• After the loop, it returns the single number found.
• Function Call & Testing:
• Two arrays '$arr1' and '$arr2' are defined with different sets of numbers.
• The "single_number()" function is called twice with these arrays as input.
• The input arrays and single numbers are printed using "print_r()".

Sample Output:

Array                                                       
(                                                           
    [0] => 5                                                
    [1] => 3                                                
    [2] => 4                                                
    [3] => 3                                                
    [4] => 4                                                
)                                                           
Single Number: 5                                            
Array                                                       
(                                                           
    [0] => 3                                                
    [1] => 2                                                
    [2] => 5                                                
    [3] => 2                                                
    [4] => 1                                                
    [5] => 5                                                
    [6] => 3                                                
)                                                           
Single Number: 1     

Flowchart:

PHP Code Editor:

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