Process rest of the elements We have three cases
return $ sum [ $ n ] = max ( max ( maxSumWO3Consec ( $ n - 1 ) , maxSumWO3Consec ( $ n - 2 ) + $ arr [ $ n ] ) , $ arr [ $ n ] + $ arr [ $ n - 1 ] + maxSumWO3Consec ( $ n - 3 ) ) ; }