Python Coding challenge - Day 542| What is the output of the following Python Code?

 

Code Explanation:

Function Definition

def peak_element(nums):

What it does: Defines a function named peak_element that takes a list of numbers nums as input.

This function is meant to find and return a "peak element"—an element that is greater than its neighbors.

Loop Through the List (Excluding First and Last Elements)

    for i in range(1, len(nums)-1):

What it does: Starts a loop from the second element (index 1) to the second last element (index len(nums)-2).

We skip the first and last elements because they don’t have two neighbors (left and right), and we're focusing on "internal" peaks.

Check for a Peak Element

        if nums[i] > nums[i-1] and nums[i] > nums[i+1]:

What it does: Checks whether the current element nums[i] is greater than both its immediate neighbors (nums[i-1] and nums[i+1]).

This condition determines if it's a peak element.

Example: In [1, 3, 20, 4, 1, 0], 20 is greater than both 3 and 4, so it's a peak.

Return the Peak if Found

            return nums[i]

What it does: If a peak is found, it is immediately returned from the function.

Fallback: Return the Maximum Element

    return max(nums)

What it does: If no peak is found in the loop (which is rare), it returns the maximum value in the list as a fallback.

This ensures the function always returns a result, even for short lists or lists with no internal peaks.

Function Call and Output

print(peak_element([1, 3, 20, 4, 1, 0]))

What it does: Calls the peak_element function with the list [1, 3, 20, 4, 1, 0] and prints the result.

What happens: The loop checks:

3 → not a peak

20 → greater than 3 and 4, so it's returned

Output: 20

Final Output

20

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