Check the wave form * If arr [ 1 ] is greater than left and right * Same pattern will be followed by whole * elements , else reverse pattern * will be followed by array elements
if ( $ arr [ 1 ] > $ arr [ 0 ] && $ arr [ 1 ] > $ arr [ 2 ] ) { for ( $ i = 1 ; $ i < ( $ n - 1 ) ; $ i += 2 ) { if ( $ arr [ $ i ] > $ arr [ $ i - 1 ] && $ arr [ $ i ] > $ arr [ $ i + 1 ] ) { $ result = true ; } else { $ result = false ; break ; } }