Final answer:
A modified binary search algorithm finds the maximum element in an array consisting of an ascending subarray followed by a descending subarray with O(logn) complexity. The algorithm searches for the transition point between ascending and descending order, the maximum is found there.
Step-by-step explanation:
A student has asked how to find the maximum element in an array that consists of an ascending subarray followed by a descending subarray, with the additional constraint of having a time complexity of O(logn). To solve this, you can apply a modified version of the binary search algorithm. Instead of searching for a specific value, the modified algorithm searches for the point where the ascending subarray ends and the descending subarray begins, which is where the maximum element will be located.
Pseudocode to find the maximum element: Set two pointers, start = 0 and end = length of the array - 1. While start is less than or equal to end: If the loop ends without finding the maximum, the maximum is at start. This algorithm takes advantage of the specific ordering in the array to quickly find the maximum value at where the order changes from ascending to descending.