981. 基于时间的键值存储

题目链接	981. 基于时间的键值存储
思路	哈希+二分
题解链接	哈希表+二分
关键点	理解题意
时间复杂度	\(O(\log n)\)
空间复杂度	\(O(n)\)

代码实现：

class TimeMap:

    def __init__(self):
        self.dct = defaultdict(list)

    def set(self, key: str, value: str, timestamp: int) -> None:
        self.dct[key].append((timestamp, value))

    def get(self, key: str, timestamp: int) -> str:
        lst = self.dct[key]
        left, right = -1, len(lst)
        while left + 1 < right:
            mid = (left + right) // 2
            if lst[mid][0] > timestamp:
                right = mid
            else:
                left = mid
        if right == 0:
            return ""
        else:
            return self.dct[key][right - 1][1]

Python-标准库

class TimeMap:

    def __init__(self):
        self.dct = defaultdict(list)

    def set(self, key: str, value: str, timestamp: int) -> None:
        self.dct[key].append((timestamp, value))

    def get(self, key: str, timestamp: int) -> str:
        upper_bound = bisect_right(self.dct[key], timestamp, key=lambda _: _[0])
        if upper_bound == 0:
            return ""
        else:
            return self.dct[key][upper_bound-1][1]