18. Find the Highest number

The problem can be found at the following link: Question Link

My Approach

• Initialize size as the size of the input vector a.

• Set low to 0 and high to size - 1.

• Enter a while loop that continues as long as low <= high.

• Calculate mid as (low + high) / 2.

• If a[mid] is greater than a[mid-1] and a[mid+1], return a[mid].

• If a[mid] is greater than a[mid-1] but less than a[mid+1], set low to mid + 1.

• Otherwise, set high to mid - 1.

• If no peak element is found, return a[size - 1].

Time and Auxiliary Space Complexity

• Time Complexity: The time complexity of this approach is O(logN), where N is the number of elements in the array.

• Auxiliary Space Complexity: The auxiliary space complexity is O(1).

Code (C++)

class Solution {
public:
    int findPeakElement(vector<int>& a) 
    {
        int size=a.size();
        int low=0, high=size-1;
        while (low<=high)
        {
            int mid=(low+high)/2;
            if (a[mid]>a[mid-1] && a[mid]>a[mid+1])
                return a[mid];
            else if (a[mid]>a[mid-1] && a[mid]<a[mid+1])
                low=mid+1;
            else high=mid-1;
        }
        return a[size-1];
    }
};

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