Return Item

TIP102 Unit 1 Session 1 Standard (Click for link to problem statements)

Problem Highlights

• 💡 Difficulty: Easy
• ⏰ Time to complete: 5 mins
• 🛠️ Topics: List Indexing, Return Statements

1: U-nderstand

Understand what the interviewer is asking for by using test cases and questions about the problem.

• Established a set (2-3) of test cases to verify their own solution later.
• Established a set (1-2) of edge cases to verify their solution handles complexities.
• Have fully understood the problem and have no clarifying questions.
• Have you verified any Time/Space Constraints for this problem?

• The function get_item() should take a list items and an integer x, and return the element at index x if it is a valid index. If x is not a valid index, the function should return None.

HAPPY CASE
Input: items = ["piglet", "pooh", "roo", "rabbit"], x = 2
Expected Output: "roo"

Input: items = ["piglet", "pooh", "roo", "rabbit"], x = 0
Expected Output: "piglet"

EDGE CASE
Input: items = ["piglet", "pooh", "roo", "rabbit"], x = 5
Expected Output: None

2: M-atch

Match what this problem looks like to known categories of problems, e.g. Linked List or Dynamic Programming, and strategies or patterns in those categories.

This problem falls under: List Indexing and Validation.

3: P-lan

Plan the solution with appropriate visualizations and pseudocode.

General Idea: Define a function that checks if the provided index is valid and returns the corresponding element if it is, or None if it isn't.

1. Define the function `get_item(items, x)`.
2. Check if `x` is within the valid range of indices for `items`.
3. If `x` is valid, return the element at index `x`.
4. If `x` is not valid, return `None`.

⚠️ Common Mistakes

• Forgetting to check if x is within the valid range.
• Not handling negative values for x.

4: I-mplement

Implement the code to solve the algorithm.

def get_item(items, x):
    # Check if x is within the valid range
    if 0 <= x < len(items):
        return items[x]
    else:
        return None

5: R-eview

Review the code by running specific example(s) and recording values (watchlist) of your code's variables along the way.

Call the function with the provided examples:

print(get_item(["piglet", "pooh", "roo", "rabbit"], 2))  # Expected Output: "roo"
print(get_item(["piglet", "pooh", "roo", "rabbit"], 5))  # Expected Output: None
print(get_item(["piglet", "pooh", "roo", "rabbit"], 0))  # Expected Output: "piglet"
print(get_item(["piglet", "pooh", "roo", "rabbit"], -1)) # Expected Output: None

Expected outputs:

"roo"
None
"piglet"
None

6: E-valuate

Evaluate the performance of your algorithm and state any strong/weak or future potential work.

• Time Complexity: O(1) since accessing an element by index in a list is a constant time operation.
• Space Complexity: O(1) as no additional data structures are used.