add 981

Author: luliyucoordinate

README.md

@@ -311,4 +311,5 @@ LeetCode
 |0978|[Longest Turbulent Subarray](https://leetcode.com/problems/longest-turbulent-subarray/) | c | [c++](./src/0978-Longest-Turbulent-Subarray/0978.cpp) |[python](./src/0978-Longest-Turbulent-Subarray/0978.py)|||Medium|
 |0979|[Distribute Coins in Binary Tree](https://leetcode.com/problems/distribute-coins-in-binary-tree/) | c | [c++](./src/0979-Distribute-Coins-in-Binary-Tree/0979.cpp) |[python](./src/0979-Distribute-Coins-in-Binary-Tree/0979.py)|||Medium|
 |0980|[Unique Paths III](https://leetcode.com/problems/unique-paths-iii/) | c | [c++](./src/0980-Unique-Paths-III/0980.cpp) |[python](./src/0980-Unique-Paths-III/0980.py)|||Medium|
-|0984|[String Without AAA or BBB](https://leetcode.com/problems/string-without-aaa-or-bbb/) | c | [c++](./src/0984-String-Without-AAA-or-BBB/0984.cpp) |[python](./src/0984-String-Without-AAA-or-BBB/0984.py)|||Medium|
+|0981|[Time Based Key-Value Store](https://leetcode.com/problems/time-based-key-value-store/) | c | [c++](./src/0981-Time-Based-Key-Value-Store/0981.cpp) |[python](./src/0981-Time-Based-Key-Value-Store/0981.py)|||Medium|
+|0984|[String Without AAA or BBB](https://leetcode.com/problems/string-without-aaa-or-bbb/) | c | [c++](./src/0984-String-Without-AAA-or-BBB/0984.cpp) |[python](./src/0984-String-Without-AAA-or-BBB/0984.py)|||Easy|

src/0981-Time-Based-Key-Value-Store/0981.cpp

@@ -0,0 +1,25 @@
+#include <string>
+#include <unordered_map>
+#include <map>
+using namespace std;
+
+static int x = [](){std::ios::sync_with_stdio(false);cin.tie(0);return 0;}();
+class TimeMap 
+{
+public:
+    /** Initialize your data structure here. */
+    TimeMap() {}
+    
+    void set(string key, string value, int timestamp) 
+    {
+        m[key].insert({timestamp, value});
+    }
+    
+    string get(string key, int timestamp) 
+    {
+        auto it = m[key].upper_bound(timestamp);
+        return it == m[key].begin() ? "" : prev(it)->second;
+    }
+private:
+    unordered_map<string, map<int, string>> m;
+};

src/0981-Time-Based-Key-Value-Store/0981.py

@@ -0,0 +1,17 @@
+import collections
+import bisect
+class TimeMap:
+    def __init__(self):
+        """
+        Initialize your data structure here.
+        """
+        self.data = collections.defaultdict(list)
+
+    def set(self, key: 'str', value: 'str', timestamp: 'int') -> 'None':
+        self.data[key].append((timestamp, value))
+
+    def get(self, key: 'str', timestamp: 'int') -> 'str':
+        if key not in self.data:
+            return ''
+        idx = bisect.bisect_right(self.data[key], (timestamp, 'z'*101))
+        return '' if idx == 0 else self.data[key][idx-1][1]