1class TimeMap:2    def __init__(self):3        self.stack = {}45    def set(self, key, value, timestamp):6        if key not in self.stack:7            self.stack[key] = []8        self.stack[key].append((value, timestamp))910    def get(self, key, timestamp):11        if key not in self.stack:12            return ""13        l = 014        r = len(self.stack[key]) - 115        while l <= r:16            m = l + ((r - l) // 2)17            if self.stack[key][m][1] == timestamp:18                return self.stack[key][m][0]19            elif self.stack[key][m][1] > timestamp:20                r = m - 121            else:22                l = m + 123        return self.stack[key][r][0] if r >= 0 else ""