|
| 1 | +from typing import List |
| 2 | + |
| 3 | + |
| 4 | +class Solution: |
| 5 | + def asteroidCollision(self, asteroids: List[int]) -> List[int]: |
| 6 | + """ |
| 7 | + 利用栈来模拟 |
| 8 | + 1. 空栈: 入栈 |
| 9 | + 2. 栈顶方向左: 入栈 |
| 10 | + 3. 栈顶方向右: |
| 11 | + a. 相同方向: 入栈 |
| 12 | + b. 相反方向: |
| 13 | + a. 栈顶 > 新行星: 跳过该行星 |
| 14 | + b. 栈顶 = 新行星: 出栈 |
| 15 | + c. 栈顶向右 < 新行星: 出栈, loop 3.c. |
| 16 | + I.没有栈顶了: 入栈该行星 |
| 17 | + II. 栈顶向左: 入栈 |
| 18 | + III. 相等: 出栈 |
| 19 | + IIII. 栈顶>新行星: 跳过该行星 |
| 20 | + """ |
| 21 | + if len(asteroids) < 2: |
| 22 | + raise KeyError |
| 23 | + stack = [] |
| 24 | + for weight in asteroids: |
| 25 | + if not stack or stack[-1] < 0: |
| 26 | + stack.append(weight) |
| 27 | + else: |
| 28 | + if stack[-1] * weight > 0: |
| 29 | + stack.append(weight) |
| 30 | + else: |
| 31 | + if stack[-1] > abs(weight): |
| 32 | + continue |
| 33 | + elif stack[-1] == abs(weight): |
| 34 | + stack = stack[:-1] |
| 35 | + else: |
| 36 | + while stack and stack[-1] > 0 and stack[-1] < abs(weight): |
| 37 | + stack = stack[:-1] |
| 38 | + if not stack or stack[-1] < 0: |
| 39 | + stack.append(weight) |
| 40 | + elif stack[-1] == abs(weight): |
| 41 | + stack = stack[:-1] |
| 42 | + elif stack[-1] > abs(weight): |
| 43 | + continue |
| 44 | + return stack |
| 45 | + |
| 46 | + |
| 47 | +if __name__ == "__main__": |
| 48 | + assert Solution().asteroidCollision(asteroids=[5, 10, -5]) == [5, 10] |
| 49 | + assert Solution().asteroidCollision(asteroids=[5, -5]) == [] |
| 50 | + assert Solution().asteroidCollision(asteroids=[10, 2, -5]) == [10] |
| 51 | + assert Solution().asteroidCollision(asteroids=[2, 10, 2, -5]) == [2, 10] |
| 52 | + assert Solution().asteroidCollision(asteroids=[2, -2, 10, 2, -5]) == [10] |
| 53 | + assert Solution().asteroidCollision(asteroids=[-2, -1, 1, 2]) == [-2, -1, 1, 2] |
| 54 | + assert Solution().asteroidCollision(asteroids=[-2, -2, 1, -2]) == [-2, -2, -2] |
| 55 | + assert Solution().asteroidCollision(asteroids=[-2, -1, 1, -2]) == [-2, -1, -2] |
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