What is the time complexity of the add method?

The time complexity of the add method is O(n + m) where n and m are the lengths of the two arrays being added.

What is the time complexity of the toString method?

The time complexity of the toString method is O(n) where n is the length of the array being converted to string.

What is the space complexity of the add method?

The space complexity of the add method is O(1) as we only use a constant amount of extra space for the sum.

What is the space complexity of the toString method?

The space complexity of the toString method is O(n) where n is the length of the array, as we need to store the resulting string.

Array Wrapper | N3mo LC

Difficulty: Easy | Acceptance: 89.10% | Paid: No Topics: N/A

Create a class ArrayWrapper that wraps an array of integers and provides the following methods:

ArrayWrapper(int[] nums): Initializes the object with the array nums.
String toString(): Returns a string representation of the wrapped array in the format “[1,2,3]“.
int add(ArrayWrapper other): Returns the sum of all elements in the current array and the other array.
Examples
Constraints
Direct Implementation
Using Built-in Methods

Examples

Example 1

Input:

nums = [[1,2],[3,4]], operation = "Add"

Output:

Explanation: const obj1 = new ArrayWrapper([1,2]); const obj2 = new ArrayWrapper([3,4]); obj1 + obj2; // 10

Example 2

Input:

nums = [[23,98,42,70]], operation = "String"

Output:

"[23,98,42,70]"

Explanation: const obj = new ArrayWrapper([23,98,42,70]); String(obj); // “[23,98,42,70]“

Example 3

Input:

nums = [[],[]], operation = "Add"

Output:

Explanation: const obj1 = new ArrayWrapper([]); const obj2 = new ArrayWrapper([]); obj1 + obj2; // 0

Constraints

0 <= nums.length <= 1000
0 <= nums[i] <= 1000

Direct Implementation

Intuition Store the array in the class and implement each method by directly iterating through the elements.

Steps

Store the array in the constructor
For toString, iterate through elements and build the string representation
For add, iterate through both arrays and sum all elements

python

class ArrayWrapper:
    def __init__(self, nums):
        self.nums = nums
    
    def add(self, other):
        total = 0
        for num in self.nums:
            total += num
        for num in other.nums:
            total += num
        return total
    
    def __str__(self):
        result = "["
        for i, num in enumerate(self.nums):
            if i &gt; 0:
                result += ","
            result += str(num)
        result += "]"
        return result

Complexity

Time: O(n + m) for add, O(n) for toString where n and m are the lengths of the arrays
Space: O(n) for toString (to store the result string), O(1) for add
Notes: Simple and straightforward implementation

Using Built-in Methods

Intuition Leverage language-specific built-in methods for array operations to simplify the code.

Steps

Store the array in the constructor
Use built-in join/toString methods for string representation
Use built-in sum/reduce methods for addition

python

class ArrayWrapper:
    def __init__(self, nums):
        self.nums = nums
    
    def add(self, other):
        return sum(self.nums) + sum(other.nums)
    
    def __str__(self):
        return "[" + ",".join(str(num) for num in self.nums) + "]"

Complexity

Time: O(n + m) for add, O(n) for toString where n and m are the lengths of the arrays
Space: O(n) for toString (to store the result string), O(1) for add
Notes: More concise code using built-in functions