Is there a two-dimensional array merging and deduplication algorithm with O(n) complexity?

Is there a two-dimensional array merging and deduplication algorithm with a complexity of O(n)

Reply content:

Is there a two-dimensional array merging and deduplication algorithm with a complexity of O(n)

<code class="php">$a = [
    ['id'=>1],
    ['id'=>2],
    ['id'=>3],
    ['id'=>4],
    ['id'=>5],
    ['id'=>6]
];
$b = [
    ['id'=>5],
    ['id'=>6],
    ['id'=>7],
];
$c = [
    ['id'=>8],
    ['id'=>9]
];

function array_unique_merge() {
    $params = func_get_args();
    $result = [];
    $hashmap = [];
    $arr_count = count($params);
    for($i = 0; $i<$arr_count; $i++) {
        foreach($params[$i] as $key => $val) {
            $md5 = md5(json_encode($val));
            if (!isset($hashmap[$md5])) {
                $hashmap[$md5] = true;
                $result[] = $val;
            }
        }
    }
    return $result;
}

print_r(array_unique_merge($a, $b, $c));</code>

I just posted my thoughts on how to do this. If n refers to the sum of the number of elements of all arrays.

This must use 2 loops. The definition of n should be the sum of the elements of multiple associative arrays. A double loop is O(n)

Serialize will be used as hash comparison in the future. What about this idea? I won’t write code for mobile phones...