How do you solve Check if Object Instance of Class on LeetCode?

Check if Object Instance of Class (LeetCode #2618) 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: Understanding the prototype chain is crucial for working with instances in JavaScript.

What is the time complexity of Check if Object Instance of Class?

The optimal solution for Check if Object Instance of Class runs in O(n) time and uses O(1) space. This complexity is linear because we are leveraging the built-in mechanisms that are optimized for checking instances.

What is the brute force solution for Check if Object Instance of Class?

The brute force approach for Check if Object Instance of Class is Brute Force, with O(n²) time complexity and O(1) space complexity. We can check if an object is an instance of a class by traversing the prototype chain manually. This means we will check each prototype until we either find the class or reach the end of the chain. The optimal Optimal Solution approach improves this to O(n).

What are the interview tips for Check if Object Instance of Class?

Always clarify the problem requirements before jumping into coding. Consider edge cases such as null or undefined inputs. Think about the efficiency of your solution and whether built-in functions can help.

What are common mistakes when solving Check if Object Instance of Class?

Confusing the difference between class instances and primitive types. Not handling null or undefined values correctly.

#2618

Check if Object Instance of Class

Medium

Prototype ChainInstance Checking

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

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Intuition

Time O(n)Space O(1)

Instead of manually traversing the prototype chain, we can use the built-in 'instanceof' operator in JavaScript, which is optimized for this purpose. This allows us to check if an object is an instance of a class or its superclass efficiently.

⚙️

Algorithm

3 steps

1Step 1: If the value is undefined or null, return false.
2Step 2: Use the instanceof operator to check if the object is an instance of the class.
3Step 3: Return the result of the instanceof check.

solution.py4 lines

1def checkIfInstanceOf(obj, cls):
2    if obj is None:
3        return False
4    return isinstance(obj, cls)

ℹ

Complexity note: This complexity is linear because we are leveraging the built-in mechanisms that are optimized for checking instances.

1Understanding the prototype chain is crucial for working with instances in JavaScript.
2Using built-in operators like instanceof can greatly simplify and optimize your solution.

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