Create a class ArrayWrapper that accepts an array of integers in its constructor. This class should have two features:
+ operator, the resulting value is the sum of all the elements in both arrays.String() function is called on the instance, it will return a comma separated string surrounded by brackets. For example, [1,2,3].Example 1:
Input: nums = [[1,2],[3,4]], operation = "Add" Output: 10 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: 0 Explanation: const obj1 = new ArrayWrapper([]); const obj2 = new ArrayWrapper([]); obj1 + obj2; // 0
Constraints:
0 <= nums.length <= 10000 <= nums[i] <= 1000Note: nums is the array passed to the constructorThe #2695 Array Wrapper problem focuses on implementing custom behavior for objects in JavaScript. You are given an array and must wrap it in a class so that instances behave correctly when used with operations like addition and string conversion.
The key idea is understanding how JavaScript converts objects into primitive values. When two wrapper objects are added using the + operator, JavaScript internally calls methods such as valueOf() or toString() to determine the primitive representation. By defining these methods in the wrapper class, you can control how the object behaves in arithmetic or string contexts.
A common approach is to compute the sum of elements in the stored array when numeric conversion occurs and return a formatted representation when the object is converted to a string. The implementation relies on built‑in JavaScript object conversion rules rather than complex data structures.
The overall logic requires iterating through the array to calculate totals when needed, resulting in linear time relative to the array length and minimal extra memory usage.
| Approach | Time Complexity | Space Complexity |
|---|---|---|
| Wrapper class with primitive conversion methods | O(n) for computing the array sum | O(1) extra space |
NeetCode
This approach leverages operator overloading (or language-specific methods) to define how instances of ArrayWrapper behave when used with the '+' operator and the String conversion function. We'll override/add appropriate methods to customize these operations:
ArrayWrapper instances.Time Complexity: O(n + m), where n and m are the lengths of the two arrays in the instances being added.
Space Complexity: O(1), as we do not use any additional space.
1class ArrayWrapper:
2 def __init__(self, nums):
3 self.nums = nums
4
5 def __add__(self, other):
6
This Python solution defines an ArrayWrapper class. It uses the magic methods __add__ for adding two instances together and __str__ for converting an instance to its string representation. __add__ method returns the sum of the numbers in both arrays, while __str__ method returns the string representation.
This approach focuses on languages that support the implementation of interfaces to achieve the desired functionality. We utilize relevant interfaces or methods required to override the behavior of arithmetic operations and object-to-string conversion.
Time Complexity: O(n + m), for summing elements of both arrays.
Space Complexity: O(1), no additional space required.
1class ArrayWrapper:
2 def __init__(self
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This problem mainly tests knowledge of JavaScript object-to-primitive conversion. It checks whether you understand how operators like + trigger valueOf or toString when dealing with custom objects.
While the exact problem may not always appear, similar questions about JavaScript object behavior and operator overloading concepts are common in frontend or JavaScript-focused interviews at top tech companies.
The problem primarily uses a simple array stored inside a wrapper class. No advanced data structures are required, but understanding class behavior and array iteration is important.
The optimal approach is to create a wrapper class and override JavaScript's primitive conversion behavior using methods like valueOf() and toString(). This allows objects to behave correctly when used in arithmetic operations or string contexts.
This Python approach assumes an interface-like setup using methods, providing add and to_string methods to implement addition and string conversion respectively.