PHP Exercises: Remove duplicates from a sorted list

Last update on April 19 2025 11:49:37 (UTC/GMT +8 hours)

35. Remove Duplicates from Sorted List

Write a PHP program to remove duplicates from a sorted list.

Input: (1,1,2,2,3,4,5,5)
Output: (1,2,3,4,5)

Sample Solution:

PHP Code:

<?php
// Function to remove duplicates from a list and return unique values
function remove_duplicates_list($list1) {
    // Use array_unique to get unique values and array_values to re-index the array
    $nums_unique = array_values(array_unique($list1));
    return $nums_unique;
}

// Example usage with an array containing duplicate values
$nums = array(1, 1, 2, 2, 3, 4, 5, 5);
// Call the function and print the result
print_r(remove_duplicates_list($nums));

?>

Explanation:

• Function Definition:
• remove_duplicates_list($list1) is a function that removes duplicate values from an array and returns an array with only unique values.
• Remove Duplicates and Re-index:
• The array_unique($list1) function filters out duplicate values from the input array $list1.
• array_values() re-indexes the filtered array so that indices are sequential (starting from 0).
• The resulting unique values array is stored in $nums_unique.
• Return Unique Values:
• The function returns $nums_unique, the array with only unique values.
• Example Usage:
• An array $nums with duplicate values is defined as [1, 1, 2, 2, 3, 4, 5, 5].
• The function remove_duplicates_list($nums) is called, and the result is printed using print_r, showing only the unique values in the array.

Output:

Array                                                       
(                                                           
    [0] => 1                                                
    [1] => 2                                                
    [2] => 3                                                
    [3] => 4                                                
    [4] => 5                                                
)             

Flowchart:

For more Practice: Solve these Related Problems:

• Write a PHP script to remove duplicates from a sorted array without using built-in array_unique() function.
• Write a PHP script to merge two pre-sorted arrays and then eliminate all duplicate values.
• Write a PHP script to remove duplicates from a sorted array and then perform a re-sort operation on the unique values.
• Write a PHP script to create a function that accepts a sorted array and returns a new array with all duplicates removed.

PHP Code Editor:

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