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Deven
37 lines
1.1 KiB
Python
37 lines
1.1 KiB
Python
class Solution:
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def asteroidCollision(self, asteroids: List[int]) -> List[int]:
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"""
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Complexities:
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Time: O(n)
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Space: O(n)
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where n = len(asteroids)
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"""
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# iterate left to right
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# - if right (+ve), keep stack
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# - if left (-ve), compare/consume top of stack
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# - - if left consume all of stack, add to output (it will survive)
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stack = []
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survivedAsteroids = []
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for i in range(len(asteroids)):
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if asteroids[i] > 0:
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stack.append(asteroids[i])
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else:
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isDestroyed = False
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while len(stack) > 0 and abs(asteroids[i]) >= stack[-1]:
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if abs(asteroids[i]) == stack[-1]:
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isDestroyed = True
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stack.pop()
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break
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stack.pop()
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if len(stack) == 0 and not isDestroyed:
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survivedAsteroids.append(asteroids[i])
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# also return stack
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survivedAsteroids += stack
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return survivedAsteroids |