Find the maximum element in an array which is first increasing and then decreasing

Here we can iterate through array to find maximum element in array by using Brute-Force method.
Its running time would be : O(n).

But still we can do it in a better way with much improved running time complexity i.e O(log(n)).
We can use binary search to solve this problem.

Please find below code in C++.


//Iterative method
int FindMax(vector<int> &aV,int aStart,int aEnd){


int lower=aStart;
int upper = aEnd;
int mid = (upper-lower)/2;
while(lower<=upper){
    if(aV[mid]>aV[mid-1] && aV[mid]>aV[mid+1]){
       cout<<"Found element"<<"\n";
       return aV[mid];
       }
    else if(aV[mid]>aV[mid-1]){
    // Search in second half
    lower = mid+1;
    mid=((upper-lower)/2)+lower;
    cout<<"moving to 2nd part: lower: "<<lower<<" mid:"<<mid<<" upper: "<<upper<<"\n";
    }else {
    // Search in First half
    upper = mid-1;    
    mid = ((upper-lower)/2)+lower;
    cout<<"moving to 1st part: lower: "<<lower<<" mid:"<<mid<<"upper: "<<upper<<"\n";
    }
                     
}
cout<<"Could not find such element"<<"\n";
return -1;  


}