## Algorithm

Problem Name: 981. Time Based Key-Value Store

Design a time-based key-value data structure that can store multiple values for the same key at different time stamps and retrieve the key's value at a certain timestamp.

Implement the `TimeMap` class:

• `TimeMap()` Initializes the object of the data structure.
• `void set(String key, String value, int timestamp)` Stores the key `key` with the value `value `at the given time `timestamp`.
• `String get(String key, int timestamp)` Returns a value such that `set` was called previously, with `timestamp_prev <= timestamp`. If there are multiple such values, it returns the value associated with the largest `timestamp_prev`. If there are no values, it returns `""`.

Example 1:

```Input
["TimeMap", "set", "get", "get", "set", "get", "get"]
[[], ["foo", "bar", 1], ["foo", 1], ["foo", 3], ["foo", "bar2", 4], ["foo", 4], ["foo", 5]]
Output
[null, null, "bar", "bar", null, "bar2", "bar2"]

Explanation
TimeMap timeMap = new TimeMap();
timeMap.set("foo", "bar", 1);  // store the key "foo" and value "bar" along with timestamp = 1.
timeMap.get("foo", 1);         // return "bar"
timeMap.get("foo", 3);         // return "bar", since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 is "bar".
timeMap.set("foo", "bar2", 4); // store the key "foo" and value "bar2" along with timestamp = 4.
timeMap.get("foo", 4);         // return "bar2"
timeMap.get("foo", 5);         // return "bar2"
```

Constraints:

• `1 <= key.length, value.length <= 100`
• `key` and `value` consist of lowercase English letters and digits.
• `1 <= timestamp <= 107`
• All the timestamps `timestamp` of `set` are strictly increasing.
• At most `2 * 105` calls will be made to `set` and `get`.

## Code Examples

### #1 Code Example with Java Programming

```Code - Java Programming```

``````
class TimeMap {

private Map();
}

public void set(String key, String value, int timestamp) {
this.map.computeIfAbsent(key, k -> new ArrayList<>()).add(new TimeStampValuePair(timestamp, value));
}

public String get(String key, int timestamp) {
if (!this.map.containsKey(key)) {
return "";
}
List < TimeStampValuePair> pairs = this.map.get(key);
int left = 0;
int right = pairs.size() - 1;
int maxIdx = -1;
while (left  < = right) {
int mid = (left + right) / 2;
if (pairs.get(mid).timestamp <= timestamp) {
maxIdx = mid;
left = mid + 1;
} else {
right = mid - 1;
}
}
return maxIdx == -1 ? "" : pairs.get(maxIdx).value;
}

private class TimeStampValuePair {
int timestamp;
String value;

public TimeStampValuePair(int timestamp, String value) {
this.timestamp = timestamp;
this.value = value;
}
}
}
``````
Copy The Code &

Input

cmd
["TimeMap", "set", "get", "get", "set", "get", "get"] [[], ["foo", "bar", 1], ["foo", 1], ["foo", 3], ["foo", "bar2", 4], ["foo", 4], ["foo", 5]]

Output

cmd
[null, null, "bar", "bar", null, "bar2", "bar2"]

### #2 Code Example with Javascript Programming

```Code - Javascript Programming```

``````
const TimeMap = function() {
this.hash = {}
};

TimeMap.prototype.set = function(key, value, timestamp) {
if(this.hash[key] == null) this.hash[key] = []
this.hash[key].push([value, timestamp])
};

TimeMap.prototype.get = function(key, timestamp) {
if(this.hash[key] == null) return ''
const arr = this.hash[key]

let l = 0, r = arr.length - 1;
while(l <= r) {
const pick = Math.floor((l + r) / 2);
if (arr[pick][1]  <  timestamp> {
l = pick + 1;
} else if (arr[pick][1] > timestamp) {
r = pick - 1
} else {
return arr[pick][0];
}
}
return arr[r]?.[0] || ''
};
``````
Copy The Code &

Input

cmd
["TimeMap", "set", "get", "get", "set", "get", "get"] [[], ["foo", "bar", 1], ["foo", 1], ["foo", 3], ["foo", "bar2", 4], ["foo", 4], ["foo", 5]]

Output

cmd
[null, null, "bar", "bar", null, "bar2", "bar2"]

### #3 Code Example with Python Programming

```Code - Python Programming```

``````
class TimeMap:

def __init__(self):
self.times = collections.defaultdict(list)
self.values = collections.defaultdict(list)

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

def get(self, key: str, timestamp: int) -> str:
i = bisect.bisect(self.times[key], timestamp)
return self.values[key][i - 1] if i else ''
``````
Copy The Code &

Input

cmd
["TimeMap", "set", "get", "get", "set", "get", "get"] [[], ["foo", "bar", 1], ["foo", 1], ["foo", 3], ["foo", "bar2", 4], ["foo", 4], ["foo", 5]]

Output

cmd
[null, null, "bar", "bar", null, "bar2", "bar2"]

### #4 Code Example with C# Programming

```Code - C# Programming```

``````
using System.Collections.Generic;

namespace LeetCode
{
public class _0981_TimeBasedKeyValueStore
{
private readonly IDictionary < string, SortedList<int, string>> map;

/** Initialize your data structure here. */
public _0981_TimeBasedKeyValueStore()
{
map = new Dictionary < string, SortedList<int, string>>();
}

public void Set(string key, string value, int timestamp)
{
if (!map.ContainsKey(key))
map.Add(key, new SortedList < int, string>());

}

public string Get(string key, int timestamp)
{
if (!map.ContainsKey(key)) return string.Empty;

var list = map[key];
for (var i = list.Count - 1; i >= 0; i--)
if (list.Keys[i]  < = timestamp)
return list.Values[i];

return string.Empty;
}
}

}
``````
Copy The Code &

Input

cmd
["TimeMap", "set", "get", "get", "set", "get", "get"] [[], ["foo", "bar", 1], ["foo", 1], ["foo", 3], ["foo", "bar2", 4], ["foo", 4], ["foo", 5]]

Output

cmd
[null, null, "bar", "bar", null, "bar2", "bar2"]