Given an array of integers representing asteroids moving in a row. Positive = right, negative = left. Equal size = both destroyed. Bigger one survives.
Return the state after all collisions. Output space-separated.
Example
Input
5,10,-5
Output
5 10
Reasoning
We start with the input array: 5, 10, -5, representing asteroids moving to the right (5, 10) and left (-5).
The asteroid -5 (moving left) collides with 5 (moving right). Since they are of equal size (∣5∣=∣−5∣), both are destroyed.
The remaining asteroid 10 (moving right) has no other asteroids to collide with, so it remains in the output.
The final output is the state after all collisions: 5 is destroyed, and 10 remains, resulting in the output: 5 10
The Asteroid Collision problem involves using a stack data structure to efficiently manage the collisions between asteroids. A stack is a Last-In-First-Out (LIFO) data structure, meaning the last element added to the stack will be the first one to be removed. This is particularly useful in this problem because we can use the stack to keep track of the asteroids that have not yet collided with other asteroids.
In the context of this problem, we need to understand the basic operations of a stack, such as push and pop. The push operation adds an element to the top of the stack, while the pop operation removes the top element from the stack. We also need to consider the concept of collision, where two asteroids of different sizes and directions interact with each other. The outcome of a collision depends on the sizes of the asteroids and their directions.
The key concept to grasp in this problem is how to use a stack to simulate the collisions between asteroids. By iterating through the array of asteroids and using the stack to keep track of the asteroids that have not yet collided, we can efficiently determine the final state of the asteroids after all collisions have occurred.
Algorithm/Approach
The general approach to solving this type of problem involves using a stack to keep track of the asteroids that have not yet collided with other asteroids. We iterate through the array of asteroids, and for each asteroid, we check if it collides with the asteroid at the top of the stack. If a collision occurs, we compare the sizes of the two asteroids and determine the outcome of the collision based on the problem's rules.
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