735. Asteroid Collision - cocoder39/coco39_LC GitHub Wiki

735. Asteroid Collision

• assuming there exists a dummy asteroid which is moving left
  • if the actual first is moving left, it can be appended
  • if the actual first is moving right, it can be appended
• assuming there exists a dummy asteroid which is moving right
  • if the actual first is moving left, there could be collision (red flag so discard this option)
  • if the actual first is moving right, it can be appended

class Solution:
    def asteroidCollision(self, asteroids: List[int]) -> List[int]:
        res = []
        for asteroid in asteroids:
            exploded = False
            while res and asteroid < 0 < res[-1]:
                if abs(asteroid) > abs(res[-1]):
                    res.pop()
                elif abs(asteroid) == abs(res[-1]):
                    exploded = True
                    res.pop()
                    break
                else:
                    exploded = True
                    break
            
            if not exploded:
                res.append(asteroid)
        return res