TemperTemper

Find Duplicate

Find the first duplicate element that appears in an array using a hash set for efficient lookup.

Code

Algorithms
$seen = [];
$dup = null;
foreach ($arr as $x) {
    if (isset($seen[$x])) { $dup = $x; break; }
    $seen[$x] = true;
}
return $dup;

Parameters

Array to check

Server

More PHP Snippets

Array Difference

Find elements in the first array that are not present in the second array.

Array Frequencies

Count how many times each value appears in an array and return a frequency map.

Array Head

Get the first n elements of an array.

Array Intersection

Find common elements that exist in both arrays.

Array Tail

Get the last n elements of an array.

Array Union

Combine two arrays and remove duplicates to produce a union.