Question

How to count the total set bits in all numbers from 1 to N in PHP

Answer 1

function count_set_bits($n) {
    $count = 0;
    while ($n) {
        $count += $n & 1;
        $n >>= 1;
    }
    return $count;
}

function count_total_set_bits($n) { 
    $setBitCount = 0; 
   
    for ($i = 1; $i <= $n; $i++) {
        $setBitCount += count_set_bits($i); 
    }
    return $setBitCount; 
} 
 
$n = 6; 
/*
    0001
    0010
    0011
    0100
    0101
    0110
*/
     
echo count_total_set_bits($n); 
 
 
 
/*
run:
      
9
     
*/

 

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