text: check if color of this city is equal to prev visited city
code: if ( col == color [ k ] ) sum += Math . max ( A * treasure [ k ] + MaxProfit ( treasure , color , n , k + 1 , color [ k ] , A , B ) , MaxProfit ( treasure , color , n , k + 1 , col , A , B ) ) ; else sum += Math . max ( B * treasure [ k ] + MaxProfit ( treasure , color , n , k + 1 , color [ k ] , A , B ) , MaxProfit ( treasure , color , n , k + 1 , col , A , B ) ) ;