#Asteroid Collision

#https://leetcode.com/problems/asteroid-collision/

class Solution(object):

def __init__(self):

self.stack = []

def logic(self, asteroids):

for asteroid in asteroids:

#if our current asteroid is positive then put it in stack.

if(asteroid >= 0):

self.stack.append(asteroid)

else:

#if our current asteroid is negative then

#if our current asteroid is bigger than the top asteroid of stack the pop it from stack

while(self.stack and abs(self.stack[-1]) < abs(asteroid) and self.stack[-1] >=0):

self.stack.pop()

#if top of stack is bigger than current asteroid than skip rest of the steps

if(self.stack and abs(self.stack[-1]) > abs(asteroid) and self.stack[-1] >=0):

continue

#if current asteroid is equal to stack top asteroid

if(self.stack and abs(self.stack[-1]) == abs(asteroid) and self.stack[-1] >=0):

self.stack.pop()

continue

#if stack is empty or is carrying negative asteroids.

if(not self.stack or self.stack[-1] < 0):

self.stack.append(asteroid)

print self.stack

def asteroidCollision(self, asteroids):

self.logic(asteroids)

"""

:type asteroids: List[int]

:rtype: List[int]

"""

#Main

obj1 = Solution()

obj1.asteroidCollision([10, 2, -5])

obj2 = Solution()

obj2.asteroidCollision([5, 10, -5])

obj3 = Solution()

obj3.asteroidCollision( [8, -8])

obj3 = Solution()

obj3.asteroidCollision( [-2, -1, 1, 2])

obj4 = Solution()

obj4.asteroidCollision( [-2,-2,-1,-2])