Find bitonic point in given bitonic sequence | Function to find bitonic point using binary search ; base condition to check if arr [ mid ] is bitonic point or not ; We assume that sequence is bitonic . We go to right subarray if middle point is part of increasing subsequence . Else we go to left subarray . ; Driver Code
< ? php function binarySearch ( $ arr , $ left , $ right ) { if ( $ left <= $ right ) { $ mid = ( $ left + $ right ) / 2 ; if ( $ arr [ $ mid - 1 ] < $ arr [ $ mid ] && $ arr [ $ mid ] > $ arr [ $ mid + 1 ] ) return $ mid ; if ( $ arr [ $ mid ] < $ arr [ $ mid + 1 ] ) return binarySearch ( $ arr , $ mid + 1 , $ right ) ; else return binarySearch ( $ arr , $ left , $ mid - 1 ) ; } return -1 ; } $ arr = array ( 6 , 7 , 8 , 11 , 9 , 5 , 2 , 1 ) ; $ n = sizeof ( $ arr ) ; $ index = binarySearch ( $ arr , 1 , $ n - 2 ) ; if ( $ index != -1 ) echo $ arr [ $ index ] ; ? >