Maximum product quadruple ( sub | Function to find a maximum product of a quadruple in array of integers of size n ; if size is less than 4 , no quadruple exists ; Sort the array in ascending order ; Return the maximum of x , y and z ; Driver Code
< ? php function maxProduct ( $ arr , $ n ) { if ( $ n < 4 ) return -1 ; sort ( $ arr ) ; $ x = $ arr [ $ n - 1 ] * $ arr [ $ n - 2 ] * $ arr [ $ n - 3 ] * $ arr [ $ n - 4 ] ; $ y = $ arr [ 0 ] * $ arr [ 1 ] * $ arr [ 2 ] * $ arr [ 3 ] ; $ z = $ arr [ 0 ] * $ arr [ 1 ] * $ arr [ $ n - 1 ] * $ arr [ $ n - 2 ] ; return max ( $ x , max ( $ y , $ z ) ) ; } $ arr = array ( -10 , -3 , 5 , 6 , -20 ) ; $ n = sizeof ( $ arr ) ; $ max = maxProduct ( $ arr , $ n ) ; if ( $ max == -1 ) echo " No ▁ Quadruple ▁ Exists " ; else echo " Maximum ▁ product ▁ is ▁ " . $ max ;