How do you solve Last Moment Before All Ants Fall Out of a Plank on LeetCode?

Last Moment Before All Ants Fall Out of a Plank (LeetCode #1503) 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: When ants meet and change directions, it can be treated as if they continue moving in their original direction.

What is the time complexity of Last Moment Before All Ants Fall Out of a Plank?

The optimal solution for Last Moment Before All Ants Fall Out of a Plank runs in O(n) time and uses O(1) space. This solution runs in O(n) time as we only need to find the maximum and minimum values from the two arrays, which is efficient.

What is the brute force solution for Last Moment Before All Ants Fall Out of a Plank?

The brute force approach for Last Moment Before All Ants Fall Out of a Plank is Brute Force, with O(n) time complexity and O(1) space complexity. The brute-force approach simulates the movement of each ant until they fall off the plank. We calculate the time it takes for each ant to reach the nearest edge of the plank, and the maximum time among all ants will be the answer. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Last Moment Before All Ants Fall Out of a Plank?

Last Moment Before All Ants Fall Out of a Plank uses the following concepts: Array, Brainteaser, Simulation. The recommended patterns to study are: Array, Simulation.

What are the interview tips for Last Moment Before All Ants Fall Out of a Plank?

Clearly explain your thought process and the reasoning behind your approach. Consider edge cases and how your solution handles them. Practice explaining your solution as if teaching someone else to solidify your understanding.

What are common mistakes when solving Last Moment Before All Ants Fall Out of a Plank?

Forgetting to handle edge cases where either left or right array is empty. Overcomplicating the simulation of ants instead of recognizing the direct calculation of fall-off times.

#1503

Last Moment Before All Ants Fall Out of a Plank

Medium

ArrayBrainteaserSimulationArraySimulation

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

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Intuition

Time O(n)Space O(1)

Instead of simulating each ant's movement, we can directly calculate the time it takes for each ant to fall off the plank based on their direction. This avoids unnecessary calculations and gives us the result in linear time.

⚙️

Algorithm

4 steps

1Step 1: Initialize a variable to keep track of the maximum time.
2Step 2: For each ant in the 'left' array, compute the time to fall off the plank (which is simply their position).
3Step 3: For each ant in the 'right' array, compute the time to fall off the plank (which is n - their position).
4Step 4: Return the maximum of these computed times.

solution.py2 lines

1def getLastMoment(n, left, right):
2    return max(max(left, default=0), n - min(right, default=n))

ℹ

Complexity note: This solution runs in O(n) time as we only need to find the maximum and minimum values from the two arrays, which is efficient.

1When ants meet and change directions, it can be treated as if they continue moving in their original direction.
2The last moment an ant falls off is determined by the furthest distance any ant has to travel to the edge.

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