Question

How to check if a number has same number of set and unset bits in PHP

Answer 1

function print_bits($n) {
    for ($i = 7; $i >= 0; $i--) {
        echo ($n >> $i) & 1;
    }
    echo "<br />";
}
 
function check_same_set_and_unset_bits($n) { 
    $set = 0;
    $unset = 0; 
     
    while ($n) { 
        if ($n & 1) {
            $set++; 
        }
        else {
            $unset++; 
        }
        $n = $n >> 1; 
    } 
     
    if ($set == $unset) {
        return true; 
    }
      
    return false; 
} 
     


$n = 178; 
     
print_bits($n);
     
if (check_same_set_and_unset_bits($n)) {
      echo "Yes<br />"; 
}
else {
      echo "No<br />"; 
}
         
$n = 179; 
     
print_bits($n);
     
if (check_same_set_and_unset_bits($n)) {
      echo "Yes<br />"; 
}
else {
      echo "No<br />"; 
}
  


  
/*
run:
       
10110010
Yes
10110011
No
      
*/

 

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