[Leetcode]981. Time Based Key-Value Store

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# [[Leetcode]981. Time Based Key-Value Store](https://leetcode.com/problems/time-based-key-value-store/) 

- 本题难度: Medium
# Description

Create a timebased key-value store class TimeMap, that supports two operations.

1. set(string key, string value, int timestamp)

• Stores the key and value, along with the given timestamp.

2. get(string key, int timestamp)

• Returns a value such that set(key, value, timestamp_prev)was called previously, with timestamp_prev <= timestamp.
• If there are multiple such values, it returns the one with the largest timestamp_prev.
• If there are no values, it returns the empty string ("").

 

Example 1:

Input: inputs = ["TimeMap","set","get","get","set","get","get"], inputs = [[],["foo","bar",1],["foo",1],["foo",3],["foo","bar2",4],["foo",4],["foo",5]]
Output: [null,null,"bar","bar",null,"bar2","bar2"]
Explanation:   
TimeMap kv;   
kv.set("foo", "bar", 1); // store the key "foo" and value "bar" along with timestamp = 1   
kv.get("foo", 1);  // output "bar"   
kv.get("foo", 3); // output "bar" since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 ie "bar"   
kv.set("foo", "bar2", 4);   
kv.get("foo", 4); // output "bar2"   
kv.get("foo", 5); //output "bar2"   

Example 2:

Input: inputs = ["TimeMap","set","set","get","get","get","get","get"], inputs = [[],["love","high",10],["love","low",20],["love",5],["love",10],["love",15],["love",20],["love",25]]
Output: [null,null,null,"","high","high","low","low"]

 

Note:

1. All key/value strings are lowercase.
2. All key/value strings have length in the range [1, 100]
3. The timestamps for all TimeMap.set operations are strictly increasing.
4. 1 <= timestamp <= 10^7
5. TimeMap.set and TimeMap.get functions will be called a total of 120000 times (combined) per test case.

# 我的代码 
```python

import heapq

class TimeMap:
    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.Stores = {}

    def set(self, key: str, value: str, timestamp: int) -> None:
        tmp = self.Stores.get(key, [])
        heapq.heappush(tmp,[timestamp, value])
        self.Stores[key] = tmp

    def get(self, key: str, timestamp: int) -> str:
        nums = self.Stores.get(key, [])

        if len(nums) == 0 or nums[0][0]>timestamp:
            return ""

        left = 0
        right = len(nums) - 1
        mid = (left + right) // 2
        while (left < right):
            if nums[mid][0] == timestamp or (
                        mid < len(nums) - 1 and nums[mid][0] < timestamp and nums[mid + 1][0] > timestamp):
                return nums[mid][1]
            if nums[mid][0] < timestamp:
                left = mid + 1
            else:
                right = mid - 1
            mid = (left + right) // 2
        if mid == len(nums) - 1 and nums[mid][0] <= timestamp:
            return nums[mid][1]
        return ""

```

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