How do you solve Calculate Money in Leetcode Bank on LeetCode?

Calculate Money in Leetcode Bank (LeetCode #1716) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(1) time complexity and O(1) space complexity. Key insight: Understanding the pattern of deposits helps in deriving a formula for the total amount.

What is the time complexity of Calculate Money in Leetcode Bank?

The optimal solution for Calculate Money in Leetcode Bank runs in O(1) time and uses O(1) space. The time complexity is O(1) because we are performing a constant number of operations regardless of the size of n.

What is the brute force solution for Calculate Money in Leetcode Bank?

The brute force approach for Calculate Money in Leetcode Bank is Brute Force, with O(n²) time complexity and O(1) space complexity. We can simulate each day Hercy deposits money and keep a running total. This approach directly follows the problem's description but can be inefficient for larger values of n. The optimal Optimal Solution approach improves this to O(1).

What algorithm or data structure is used to solve Calculate Money in Leetcode Bank?

Calculate Money in Leetcode Bank uses the following concepts: Math. The recommended patterns to study are: Arithmetic Series, Mathematical Summation.

What are the interview tips for Calculate Money in Leetcode Bank?

Always explain your thought process clearly while coding. Consider edge cases, such as n being less than 7. Practice deriving formulas from patterns, as this can save time in interviews.

What are common mistakes when solving Calculate Money in Leetcode Bank?

Forgetting to account for the increment of deposits each week. Confusing the number of weeks and days when calculating the total.

#1716

Calculate Money in Leetcode Bank

Easy

MathArithmetic SeriesMathematical Summation

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

💡

Intuition

Time O(1)Space O(1)

Instead of simulating each day, we can use a mathematical approach to calculate the total deposits based on the number of complete weeks and the remaining days.

⚙️

Algorithm

3 steps

1Step 1: Calculate the number of complete weeks in n and the remaining days.
2Step 2: Use the formula for the sum of an arithmetic series to calculate the total for complete weeks.
3Step 3: Calculate the total for the remaining days using the last week's deposit amount.

solution.py5 lines

1def totalMoney(n):
2    weeks = n // 7
3    days = n % 7
4    total = (28 * weeks) + (weeks * (weeks - 1) // 2 * 7) + (days * (days + 1) // 2 + weeks * days)
5    return total

ℹ

Complexity note: The time complexity is O(1) because we are performing a constant number of operations regardless of the size of n.

1Understanding the pattern of deposits helps in deriving a formula for the total amount.
2Recognizing the arithmetic series can simplify calculations significantly.

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