How do you solve Earliest Finish Time for Land and Water Rides II on LeetCode?

Earliest Finish Time for Land and Water Rides II (LeetCode #3635) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n log n + m log m) time complexity and O(n + m) space complexity. Key insight: Sort rides by start time to streamline calculations.

What is the time complexity of Earliest Finish Time for Land and Water Rides II?

The optimal solution for Earliest Finish Time for Land and Water Rides II runs in O(n log n + m log m) time and uses O(n + m) space. Sorting the rides takes O(n log n) and O(m log m), and the subsequent calculations are linear.

What is the brute force solution for Earliest Finish Time for Land and Water Rides II?

The brute force approach for Earliest Finish Time for Land and Water Rides II is Brute Force, with O(n²) time complexity and O(1) space complexity. Try every combination of land and water rides. Calculate the finish time for each combination and find the minimum. This approach is straightforward but inefficient. The optimal Optimal Solution approach improves this to O(n log n + m log m).

What algorithm or data structure is used to solve Earliest Finish Time for Land and Water Rides II?

Earliest Finish Time for Land and Water Rides II uses the following concepts: Array, Two Pointers, Binary Search, Greedy, Sorting. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Earliest Finish Time for Land and Water Rides II?

Clarify the problem requirements before coding. Discuss your thought process and approach with the interviewer. Practice similar problems to build intuition.

What are common mistakes when solving Earliest Finish Time for Land and Water Rides II?

Forgetting to account for waiting times between rides. Not considering both orders of rides.

#3635

Earliest Finish Time for Land and Water Rides II

Medium

ArrayTwo PointersBinary SearchGreedySortingHash MapArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n log n + m log m)
Space	O(1)	O(n + m)

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Intuition

Time O(n log n + m log m)Space O(n + m)

Sort both ride types by start time. Use prefix and suffix arrays to efficiently calculate the earliest finish time for both ride orders.

⚙️

Algorithm

3 steps

1Step 1: Sort land and water rides by start time.
2Step 2: Create prefix minimums for land ride finish times and suffix minimums for water ride finish times.
3Step 3: Calculate the minimum finish time for both orders using the prefix and suffix arrays.

solution.py13 lines

1def earliestFinish(landStart, landDuration, waterStart, waterDuration):
2    land = sorted(zip(landStart, landDuration))
3    water = sorted(zip(waterStart, waterDuration))
4    landFinish = [0] * len(land)
5    waterFinish = [0] * len(water)
6    for i in range(len(land)):
7        landFinish[i] = land[i][0] + land[i][1] if i == 0 else max(landFinish[i-1], land[i][0] + land[i][1])
8    for i in range(len(water)-1, -1, -1):
9        waterFinish[i] = water[i][0] + water[i][1] if i == len(water)-1 else min(waterFinish[i+1], water[i][0] + water[i][1])
10    minFinish = float('inf')
11    for i in range(len(land)):
12        minFinish = min(minFinish, max(landFinish[i], waterFinish[i]))
13    return minFinish

ℹ

Complexity note: Sorting the rides takes O(n log n) and O(m log m), and the subsequent calculations are linear.

1Sort rides by start time to streamline calculations.
2Use prefix and suffix arrays to avoid redundant calculations.

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