How do you solve Array Prototype Last on LeetCode?

Array Prototype Last (LeetCode #2619) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(1) time complexity and O(1) space complexity. Key insight: Understanding how to extend built-in objects like arrays is crucial in JavaScript.

What is the brute force solution for Array Prototype Last?

The brute force approach for Array Prototype Last is Brute Force, with O(1) time complexity and O(1) space complexity. The brute force approach simply checks if the array has any elements. If it does, it retrieves the last element using the length property. If the array is empty, it returns -1. The optimal Optimal Solution approach improves this to O(1).

What are the interview tips for Array Prototype Last?

Always clarify the requirements and edge cases before coding. Explain your thought process as you write the code. Test your solution with different inputs, including edge cases.

What are common mistakes when solving Array Prototype Last?

Forgetting to check if the array is empty before accessing elements. Confusing the use of 'this' in the context of array methods.

#2619

Array Prototype Last

Easy

Array

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(1)	O(1)
Space	O(1)	O(1)

💡

Intuition

Time O(1)Space O(1)

The optimal solution is essentially the same as the brute force approach since accessing the last element of an array is inherently efficient. We can directly implement the method without any additional checks.

⚙️

Algorithm

2 steps

1Step 1: Define a method on Array.prototype called last.
2Step 2: Return the last element if the array has elements, otherwise return -1.

solution.py4 lines

1def last(self):
2    return self[-1] if len(self) > 0 else -1
3
4setattr(list, 'last', last)

ℹ

Complexity note: The time complexity remains O(1) as we are directly accessing the last element. The space complexity is O(1) since no extra space is used.

1Understanding how to extend built-in objects like arrays is crucial in JavaScript.
2Directly accessing array elements is efficient and should be leveraged.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.