How do you solve Collecting Chocolates on LeetCode?

Collecting Chocolates (LeetCode #2735) 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: Performing operations incurs a cost, so we need to balance between collecting chocolates and the cost of rotations.

What is the brute force solution for Collecting Chocolates?

The brute force approach for Collecting Chocolates is Brute Force, with O(n²) time complexity and O(1) space complexity. In the brute-force approach, we try every possible way to collect chocolates by simulating all possible rotations and calculating the total cost for each. This method is straightforward but inefficient as it checks all combinations. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Collecting Chocolates?

Collecting Chocolates uses the following concepts: Array, Enumeration. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Collecting Chocolates?

Always think about how to optimize a brute-force solution. Look for patterns in the problem that can simplify calculations. Make sure to dry-run your solution with examples to catch edge cases.

What are common mistakes when solving Collecting Chocolates?

Forgetting to account for the cost of rotations when calculating total costs. Not considering the minimum cost across all rotations.

#2735

Collecting Chocolates

Medium

ArrayEnumerationHash MapArray

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)

In the optimal solution, we recognize that we can calculate the total cost for each chocolate type directly without simulating every rotation. We can use a single pass to determine the minimum cost based on the number of rotations.

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Algorithm

4 steps

1Step 1: Initialize a variable to store the total cost of collecting all chocolates without any rotations.
2Step 2: For each chocolate type, calculate the total cost including the cost of rotations.
3Step 3: Compare the cost of collecting chocolates directly with the cost of performing rotations and update the minimum cost.
4Step 4: Return the minimum cost.

solution.py8 lines

1def minCost(nums, x):
2    n = len(nums)
3    total_cost = sum(nums)
4    min_cost = total_cost
5    for rotation in range(n):
6        current_cost = total_cost + rotation * x
7        min_cost = min(min_cost, current_cost)
8    return min_cost

ℹ

Complexity note: The time complexity is O(n) because we only need to sum the costs once and then iterate through the rotations, making it much more efficient than the brute-force approach.

1Performing operations incurs a cost, so we need to balance between collecting chocolates and the cost of rotations.
2The optimal solution reduces the number of calculations by leveraging the total cost of chocolates.

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