Geocaching

TIP102 Unit 6 Session 2 Standard (Click for link to problem statements)

Problem Highlights

• 💡 Difficulty: Easy
• ⏰ Time to complete: 10-15 mins
• 🛠️ Topics: Linked Lists, Binary to Decimal Conversion

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?

• What does the problem ask for?
  • The problem asks to convert a binary number represented by a linked list of 0s and 1s into its decimal equivalent.
• What should be returned?
  • The function should return the decimal value of the binary sequence.

HAPPY CASE
Input: cache_labels = Node(1, Node(0, Node(1)))  # Binary: 101
Output: 5
Explanation: The binary number 101 corresponds to the decimal value 5.

EDGE CASE
Input: cache_labels = Node(0)  # Binary: 0
Output: 0
Explanation: The binary number 0 corresponds to the decimal value 0.

EDGE CASE
Input: cache_labels = Node(1)  # Binary: 1
Output: 1
Explanation: The binary number 1 corresponds to the decimal value 1.

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.

For Linked List problems involving Binary to Decimal Conversion, we want to consider the following approaches:

• Traversal: Traverse the linked list while building the decimal number using binary arithmetic.

3: P-lan

Plan the solution with appropriate visualizations and pseudocode.

General Idea: We will traverse the linked list from the head, treating the linked list as a binary number. As we traverse, we will shift the current result left by one bit (multiplying by 2) and then add the current node's value.

1) Initialize a variable `result` to 0.
2) Traverse the linked list:
    a) For each node, multiply `result` by 2 and add the node's value to `result`.
    b) Move to the next node.
3) Return the final value of `result`.

⚠️ Common Mistakes

• Forgetting to handle cases where the list is empty.
• Misunderstanding the binary to decimal conversion process.

4: I-mplement

Implement the code to solve the algorithm.

class Node:
    def __init__(self, value, next=None):
        self.value = value
        self.next = next

# Function to convert binary linked list to decimal value
def locate_cache(cache_labels):
    result = 0
    current = cache_labels
    
    while current:
        result = result * 2 + current.value
        current = current.next
    
    return result

5: R-eview

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

• Example: Use the provided cache_labels linked list to verify that the function correctly converts the binary sequence to a decimal number.

6: E-valuate

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

Assume N represents the number of nodes in the linked list.

• Time Complexity: O(N) because each node is visited exactly once.
• Space Complexity: O(1) because the algorithm uses a constant amount of extra space for the result and pointers.