Question

How to find the number occurring an odd number of times in an array with PHP

Answer 1

function get_number_that_occurring_an_odd_number_of_times_in_array(&$arr) {
    $size = count($arr);
    $value = 0;
     
    for ($i = 0; $i < $size; $i++) {
        $value ^= $arr[$i];
    }
     
    for ($i = 0; $i < $size; $i++) {
        if ($arr[$i] == $value) {
            return $value;
        }
    }

    return -1;
}
     
$arr = array(1, 1, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5);
 
echo get_number_that_occurring_an_odd_number_of_times_in_array($arr);

 
 
/*
run:
 
3
 
*/

 

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