[Python3] priority queue
Please check out this commit for solutions of weekly 400 in C++, Java, Python, Javascript, Typescript. \n\n\nclass Solution:\n    def clearStars(self, s: str) -
Please check out this [commit](https://github.com/gaosanyong/leetcode/commit/bff6a0f3ec96f274af106541d85a4c48c6a0af82) for solutions of weekly 400 in C++, Java, Python, Javascript, Typescript. \n\n```\nclass Solution:\n    def clearStars(self, s: str) -> str:\n        s = list(s)\n        pq = []\n        for i, ch in enumerate(s): \n            if ch == \'*\': s[-heappop(pq)[1]] = \'*\'\n            else: heappush(pq, (ch, -i))\n        return \'\'.join(s).replace(\'*\', \'\')\n```
['Python3']