Question

Could you plese help me to create an optimized php custom function for sorting a binary array ? Now, I am using the bubble sort algorithm with two for loops. My code given below :

for ( $i = 0; $i < $array_size; $i++ )  
{  
   for ($j = 0; $j < $array_size; $j++ )  
   {  
      if ($numbers[$i] < $numbers[$j])  
      {  
         $temp = $numbers[$i];  
         $numbers[$i] = $numbers[$j];  
         $numbers[$j] = $temp;  
      }  
   }  
}

Answer 1

Bubble sort in an O(N^2) you can use the below approach which is O(N):

1. Find the sum of all elements in the array. It’ll give you the number of 1‘s in the array. You can use the array_sum() function for this. Call the result s. Also let n be the number of elements in the array.

2. The sorted array will have n-s number of 0s followed by s number of 1‘s.

Note that you can’t do better than O(N) as you must touch each array element once.