Maximum product of a triplet ( subsequence of size 3 ) in array | Function to find a maximum product of a triplet in array of integers of size n ; if size is less than 3 , no triplet exists ; Sort the array in ascending order ; Return the maximum of product of last three elements and product of first two elements and last element ; Driver code
< ? php function maxProduct ( $ arr , $ n ) { if ( $ n < 3 ) { return -1 ; } sort ( $ arr ) ; return max ( $ arr [ 0 ] * $ arr [ 1 ] * $ arr [ $ n - 1 ] , $ arr [ $ n - 1 ] * $ arr [ $ n - 2 ] * $ arr [ $ n - 3 ] ) ; } $ arr = array ( -10 , -3 , 5 , 6 , -20 ) ; $ n = sizeof ( $ arr ) ; $ max = maxProduct ( $ arr , $ n ) ; if ( $ max == -1 ) { echo ( " No ▁ Triplet ▁ Exists " ) ; } else { echo ( " Maximum ▁ product ▁ is ▁ " . $ max ) ; }