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TimeBasedKeyValueStorage.java
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TimeBasedKeyValueStorage.java
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package Leetcode;
import java.sql.Time;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @author kalpak
*
* 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:
*
* All key/value strings are lowercase.
* All key/value strings have length in the range [1, 100]
* The timestamps for all TimeMap.set operations are strictly increasing.
* 1 <= timestamp <= 10^7
* TimeMap.set and TimeMap.get functions will be called a total of 120000 times (combined) per test case.
*/
class Data {
String value;
int timestamp;
public Data(String value, int timestamp) {
this.value = value;
this.timestamp = timestamp;
}
}
public class TimeBasedKeyValueStorage {
Map<String, List<Data>> map;
public TimeBasedKeyValueStorage() {
map = new HashMap<>();
}
public void set(String key, String value, int timestamp) {
map.computeIfAbsent(key, k -> new ArrayList<>()).add(new Data(value, timestamp));
}
public String get(String key, int timestamp) {
if(!map.containsKey(key))
return "";
List<Data> data = map.get(key);
int left = 0;
int right = data.size() - 1;
int resultIdx = -1;
while(left <= right) {
int mid = left + (right - left)/2;
if(data.get(mid).timestamp <= timestamp) {
resultIdx = mid; // possible candidate
left = mid + 1;
} else
right = mid - 1;
}
return (resultIdx == -1) ? "" : data.get(resultIdx).value;
}
public static void main(String[] args) {
TimeBasedKeyValueStorage obj = new TimeBasedKeyValueStorage();
obj.set("foo","bar",1);
System.out.println(obj.get("foo", 1));
System.out.println(obj.get("foo", 3));
obj.set("foo","bar2",4);
System.out.println(obj.get("foo", 4));
System.out.println(obj.get("foo", 5));
}
}