Getting all nodes at a level in full binary tree, array format

Question

I need to get all the nodes at a certain level in a full binary tree from either the left or right subtree. I currently retrieve the binary tree from the DB as an array, for exa

Answer 1

I upvoted BeetleJuice's answer for using the "Shift Left" bitwise operator << -- it is the perfect building block for this task.

This is as clean as I can make my coding attempt:

Code: (Demo)

function getForkinValues($array,$level,$side='left'){ // left side fork is default
    if($level==1) return current($array);
    $length=$level>2?1<<($level-2):1;  // number of elements to return
    $index=(1<<$level-1)-1;            // first index to return
    if($side=='right') $index+=$length;  // shift to correct index for 'right'
    if(!isset($array[$index+$length-1])) return 'Error: Insufficient Array Length';
    return array_slice($array,$index,$length);

}
$array=['A','B','C','D','E','F','G'];
var_export(getForkinValues($array,3,'right'));