text: If it is covered
code: if ( covered > 0 ) { return dp [ root . data , covered , compulsory ] = Math . Min ( 1 + minDominatingSet ( root . left , 1 , 0 ) + minDominatingSet ( root . right , 1 , 0 ) , minDominatingSet ( root . left , 0 , 0 ) + minDominatingSet ( root . right , 0 , 0 ) ) ; }