How do you solve Array Wrapper on LeetCode?

Array Wrapper (LeetCode #2695) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(1) space complexity. Key insight: Precomputing values can significantly reduce time complexity.

What is the brute force solution for Array Wrapper?

The brute force approach for Array Wrapper is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach involves manually summing the elements of both arrays whenever two instances are added. This is straightforward but inefficient, as it requires iterating through both arrays each time an addition is performed. The optimal Optimal Solution approach improves this to O(n).

What are the interview tips for Array Wrapper?

Explain your thought process clearly when implementing operator overloading. Consider edge cases like empty arrays upfront. Discuss time and space complexity as you develop your solution.

What are common mistakes when solving Array Wrapper?

Forgetting to handle empty arrays properly. Not using constructor to initialize sums.

#2695

Array Wrapper

Easy

ArrayOperator Overloading

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(1)

💡

Intuition

Time O(n)Space O(1)

The optimal solution involves storing the sum of the array elements during initialization. This way, we can directly return the precomputed sum during addition, making the operation much faster.

⚙️

Algorithm

3 steps

1Step 1: Create a class ArrayWrapper that initializes with an array of integers and calculates the sum during initialization.
2Step 2: Implement the __add__ method to return the sum of precomputed sums of both instances.
3Step 3: Implement the __str__ method to return a string representation of the array in the required format.

solution.py10 lines

1class ArrayWrapper:
2    def __init__(self, arr):
3        self.arr = arr
4        self.sum = sum(arr)
5    
6    def __add__(self, other):
7        return self.sum + other.sum
8    
9    def __str__(self):
10        return str(self.arr).replace(' ', '')

ℹ

Complexity note: The time complexity is O(n) for the initialization of the array, but the addition operation is O(1) since we are using precomputed sums.

1Precomputing values can significantly reduce time complexity.
2Understanding operator overloading can enhance class functionality.

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