Sum of Cards - codepath/compsci_guides GitHub Wiki

Unit 5 Session 1 (Click for link to problem statements)

U-nderstand

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

• What should happen if there are no cards in the hand?
  • The function should return 0 as the sum, assuming all cards are valid or there are no cards.

P-lan

Plan the solution with appropriate visualizations and pseudocode.

General Idea: Calculate the total value of all cards in a Hand instance, checking each card's validity before summing their values.

1) Initialize a variable `total` to `0` to store the cumulative value of the cards.
2) Iterate over each card in the hand.
3) Check if the card is valid using the `is_valid()` method.
  a) If any card is invalid, immediately return `None`.
4) If the card is valid, add its value (obtained from `get_value()`) to `total`.
5) After all cards have been processed, return the value of `total`.

⚠️ Common Mistakes

• Neglecting to check the validity of each card, which could lead to adding incorrect values.
• Incorrectly handling or ignoring the None return condition for invalid cards.

I-mplement

def sum_hand(hand):
    total = 0
    for card in hand.cards:
        if not card.is_valid():
            return None
        total += card.get_value()
    return total