LeetCode Problem Workspace
Array Wrapper
The Array Wrapper problem focuses on implementing a class that wraps an array to perform operations like addition or string conversion.
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Easy · Array Wrapper core interview pattern
Answer-first summary
The Array Wrapper problem focuses on implementing a class that wraps an array to perform operations like addition or string conversion.
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The Array Wrapper class requires implementing functionality for adding arrays and converting them to string representations. It tests understanding of basic class design and operator overloading in JavaScript. The main focus is on handling array operations in a custom wrapper class efficiently.
Problem Statement
You are asked to create a class called ArrayWrapper that takes an array of integers as an argument in its constructor. The class should support two operations: adding two ArrayWrapper objects, and converting an ArrayWrapper object to a string representation of the array. When adding two objects, the elements of the arrays should be summed up, and when converting to a string, the array should be displayed in the typical array format.
Your task is to implement the ArrayWrapper class that supports these operations. The input will be an array of integers, and your class should define how to handle both the 'Add' and 'String' operations when used with instances of the ArrayWrapper class. For example, if you add two ArrayWrapper instances, their arrays should be added element-wise, and if you convert an instance to a string, it should return the array in string format.
Examples
Example 1
Input: nums = [[1,2],[3,4]], operation = "Add"
Output: 10
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]"
const obj = new ArrayWrapper([23,98,42,70]); String(obj); // "[23,98,42,70]"
Example 3
Input: nums = [[],[]], operation = "Add"
Output: 0
const obj1 = new ArrayWrapper([]); const obj2 = new ArrayWrapper([]); obj1 + obj2; // 0
Constraints
- 0 <= nums.length <= 1000
- 0 <= nums[i] <= 1000
- Note: nums is the array passed to the constructor
Solution Approach
Class Construction
Start by defining the ArrayWrapper class with an appropriate constructor that accepts an array. You’ll need to store the array and define the methods for the required operations.
Operator Overloading
Use the JavaScript valueOf() and toString() methods to overload the '+' and 'String' operators. Implement valueOf() to return the sum of the arrays and toString() to return the array as a string.
Testing Edge Cases
Ensure that your solution handles edge cases, such as empty arrays or arrays with varying lengths. This will ensure robustness and correctness.
Complexity Analysis
| Metric | Value |
|---|---|
| Time | Depends on the final approach |
| Space | Depends on the final approach |
The time complexity depends on the size of the arrays being added or converted. For each operation, the complexity will be O(n) where n is the number of elements in the array.
What Interviewers Usually Probe
- Candidate demonstrates familiarity with JavaScript class methods and operator overloading.
- Candidate uses efficient array manipulation techniques.
- Candidate handles edge cases like empty arrays properly.
Common Pitfalls or Variants
Common pitfalls
- Not handling empty arrays or incorrect assumptions about array lengths.
- Misusing JavaScript’s built-in methods for operator overloading.
- Failing to test edge cases like arrays with different sizes.
Follow-up variants
- Change the operation to subtract arrays instead of adding them.
- Allow custom operations (e.g., multiplication) between ArrayWrapper objects.
- Implement a compare function to check if two ArrayWrapper objects are equal.
FAQ
What is the key challenge in solving the Array Wrapper problem?
The main challenge lies in correctly implementing operator overloading and ensuring that array operations like addition and string conversion work as expected.
How can I handle edge cases in the Array Wrapper problem?
Edge cases like empty arrays or mismatched array lengths can be handled by validating inputs and ensuring robust array manipulation.
Can the Array Wrapper problem be solved without using operator overloading?
While it’s possible, the primary objective of the problem is to practice operator overloading, which is a core part of the solution.
What do I need to focus on when implementing the Array Wrapper class?
Focus on proper class construction, implementing operator overloading for both addition and string conversion, and testing edge cases.
How is the Array Wrapper problem relevant to interviews?
This problem tests your understanding of object-oriented principles, JavaScript-specific methods like valueOf() and toString(), and the ability to handle array operations efficiently.
Solution
Solution 1
#### TypeScript
class ArrayWrapper {
private nums: number[];
private s: number;
constructor(nums: number[]) {
this.nums = nums;
this.s = nums.reduce((a, b) => a + b, 0);
}
valueOf() {
return this.s;
}
toString() {
return `[${this.nums}]`;
}
}
/**
* const obj1 = new ArrayWrapper([1,2]);
* const obj2 = new ArrayWrapper([3,4]);
* obj1 + obj2; // 10
* String(obj1); // "[1,2]"
* String(obj2); // "[3,4]"
*/