# 20.07.2023 [735. Asteroid Collision]

Result after asteroids collide left-right exploding by size: `15 5 -15 -5 5 -> -15 -5 5`

20.07.2023

735. Asteroid Collision medium
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Problem TLDR

Result after asteroids collide left-right exploding by size: 15 5 -15 -5 5 -> -15 -5 5

Intuition

Let’s add positive asteroids to the Stack. When negative met, it can fly over all smaller positive added, and can explode if larger met.

Approach

Kotlin’s API helping reduce some LOC

Complexity

• Time complexity:
  O(n)

• Space complexity:
  O(n)

Code

    fun asteroidCollision(asteroids: IntArray): IntArray = with(Stack<Int>()) {
        asteroids.forEach { sz ->
          if (!generateSequence { if (sz > 0 || isEmpty() || peek() < 0) null else peek() }
            .any {
              if (it <= -sz) pop()
              it >= -sz
            }) add(sz)
        }
        toIntArray()
    }