981. Time Based Key-Value Store

https://leetcode.com/problems/time-based-key-value-store/

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.

---

	class Pair {
	Integer timestamp;
	String value;
	public Pair(int t, String v) {
	timestamp = t;
	value = v;
	}
	}
	class TimeMap {
	Map<String, List<Pair>> map;
	/** Initialize your data structure here. */
	public TimeMap() {
	map = new HashMap<String, List<Pair>>();
	}
	public void set(String key, String value, int timestamp) {
	map.putIfAbsent(key, new ArrayList<Pair>());
	map.get(key).add(new Pair(timestamp, value));
	}
	public String get(String key, int timestamp) {
	if (!map.containsKey(key) || timestamp < map.get(key).get(0).timestamp) {
	return "";
	}
	List<Pair> list = map.get(key);
	int lo = 0, hi = list.size() - 1;
	String ans = "";
	while (lo <= hi) {
	int mid = lo + (hi - lo) / 2;
	int t = list.get(mid).timestamp;
	if (t == timestamp) {
	return list.get(mid).value;
	}
	if (t < timestamp) {
	ans = list.get(mid).value;
	lo = mid + 1;
	} else {
	hi = mid - 1;
	}
	}
	return ans;
	}
	}
	/**
	* Your TimeMap object will be instantiated and called as such:
	* TimeMap obj = new TimeMap();
	* obj.set(key,value,timestamp);
	* String param_2 = obj.get(key,timestamp);
	*/

view raw 981.TimeBasedKeyValueStoreMapWithBinarySearch.java hosted with ❤ by GitHub

	class TimeMap {
	Map<String, TreeMap<Integer, String>> map;
	/** Initialize your data structure here. */
	public TimeMap() {
	map = new HashMap<String, TreeMap<Integer, String>>();
	}
	public void set(String key, String value, int timestamp) {
	map.putIfAbsent(key, new TreeMap<Integer, String>());
	map.get(key).put(timestamp, value);
	}
	public String get(String key, int timestamp) {
	if (!map.containsKey(key) || map.get(key).floorKey(timestamp) == null) {
	return "";
	}
	return map.get(key).get(map.get(key).floorKey(timestamp));
	}
	}
	/**
	* Your TimeMap object will be instantiated and called as such:
	* TimeMap obj = new TimeMap();
	* obj.set(key,value,timestamp);
	* String param_2 = obj.get(key,timestamp);
	*/

view raw 981.TimeBasedKeyValueStoreMapWithTreeMap.java hosted with ❤ by GitHub

	class TimeMap:
	def __init__(self):
	self.map = {}
	def set(self, key: str, value: str, timestamp: int) -> None:
	if not key in self.map:
	self.map[key] = []
	self.map[key].append((timestamp, value))
	def get(self, key: str, timestamp: int) -> str:
	if not key in self.map or timestamp < self.map[key][0][0]:
	return ""
	list = self.map[key]
	lo = 0
	hi = len(list) - 1
	ans = ""
	while lo <= hi:
	mid = (hi + lo) // 2;
	t = list[mid][0]
	if t == timestamp:
	return list[mid][1]
	if t < timestamp:
	ans = list[mid][1]
	lo = mid + 1
	else:
	hi = mid - 1
	return ans
	# Your TimeMap object will be instantiated and called as such:
	# obj = TimeMap()
	# obj.set(key,value,timestamp)
	# param_2 = obj.get(key,timestamp)

view raw 981.TimeBasedKey-ValueStore.py hosted with ❤ by GitHub