feat: resolve time based key value store

Feat time based key value store

Author: bujosa

src/medium/time_based_key_value_store.rs

@@ -1,36 +1,73 @@
 #![allow(dead_code)]
-struct TimeMap {}
+use std::collections::HashMap;
 
 /**
- * `&self` means the method takes an immutable reference.
- * If you need a mutable reference, change it to `&mut self` instead.
+ * Your TimeMap object will be instantiated and called as such:
+ * let obj = TimeMap::new();
+ * obj.set(key, value, timestamp);
+ * let ret_2: String = obj.get(key, timestamp);
  */
+struct TimeMap {
+    hm: HashMap<String, Vec<(String, i32)>>,
+}
+
 impl TimeMap {
     fn new() -> Self {
-        TimeMap {}
+        Self { hm: HashMap::new() }
     }
 
-    fn set(&self, key: String, value: String, timestamp: i32) {}
+    fn set(&mut self, key: String, value: String, timestamp: i32) {
+        self.hm.entry(key).or_default().push((value, timestamp));
+    }
 
     fn get(&self, key: String, timestamp: i32) -> String {
-        "".to_string()
+        let mut res = String::new();
+
+        if let Some(t_list) = self.hm.get(&key) {
+            let (mut l, mut r) = (0, t_list.len());
+
+            while l < r {
+                let m = l + (r - l) / 2;
+                if timestamp < t_list[m].1 {
+                    r = m;
+                } else {
+                    res = t_list[m].0.clone();
+                    l = m + 1;
+                }
+            }
+        }
+
+        res
     }
 }
 
-/**
- * Your TimeMap object will be instantiated and called as such:
- * let obj = TimeMap::new();
- * obj.set(key, value, timestamp);
- * let ret_2: String = obj.get(key, timestamp);
- */
+/*
+    Algorithm - Binary Search
+
+    - Create a HashMap with key as String and value as Vec<(String, i32)>
+    - set(key, value, timestamp)
+        - Insert the key into the HashMap if it doesn't exist
+        - Push the value and timestamp into the Vec
+    - get(key, timestamp)
+        - If the key doesn't exist, return empty string
+        - If the key exists, do binary search on the Vec<(String, i32)>
+            - If the timestamp is less than the middle element's timestamp, search the left half
+            - If the timestamp is greater than or equal to the middle element's timestamp, search the right half
+            - If the timestamp is equal to the middle element's timestamp, return the value
+            - If the timestamp is greater than the middle element's timestamp, return the value of the right element
+            - If the timestamp is less than the middle element's timestamp, return the value of the left element
+
+    Time    O(logN)
+    Space   O(N)
+*/
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[test]
-    fn test_981() {
-        let obj = TimeMap::new();
+    fn test_1() {
+        let mut obj = TimeMap::new();
         obj.set("foo".to_string(), "bar".to_string(), 1);
         assert_eq!(obj.get("foo".to_string(), 1), "bar".to_string());
         assert_eq!(obj.get("foo".to_string(), 3), "bar".to_string());

src/readme.md

@@ -66,7 +66,7 @@
   - [x] [739. Daily temperatures](../src/medium/daily_temperatures.rs) -> [Problem Description](../src/medium/readme.md#739-daily-temperatures)
   - [x] [853. Car fleet](../src/medium/car_fleet.rs) -> [Problem Description](../src/medium/readme.md#853-car-fleet)
   - [x] [875. Koko eating bananas](../src/medium/koko_eating_bananas.rs) -> [Problem Description](../src/medium/readme.md#875-koko-eating-bananas)
-  - [ ] [981. Time based key-value store](../src/medium/time_based_key_value_store.rs) -> [Problem Description](../src/medium/readme.md#981-time-based-key-value-store)
+  - [x] [981. Time based key-value store](../src/medium/time_based_key_value_store.rs) -> [Problem Description](../src/medium/readme.md#981-time-based-key-value-store)
 - [Hard](../src/hard)
   - [x] [42. Trapping rain water](../src/hard/trapping_rain_water.rs) -> [Problem Description](../src/hard/readme.md#42-trapping-rain-water)
   - [x] [76. Minimum window substring](../src/hard/minimum_window_substring.rs) -> [Problem Description](../src/hard/readme.md#76-minimum-window-substring)

theory/categories/3.binary_search/readme.md

@@ -33,11 +33,11 @@
 - [x] [koko Eating Bananas](https://leetcode.com/problems/koko-eating-bananas/) | Medium | [Solution](../../../src/medium/koko_eating_bananas.rs) | [Problem Description](../../../src/medium/readme.md#875-koko-eating-bananas)
 - [x] [Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/) | Medium | [Solution](../../../src/medium/find_minimum_in_rotated_sorted_array.rs) | [Problem Description](../../../src/medium/readme.md#153-find-minimum-in-rotated-sorted-array)
 - [x] [Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/) | Medium | [Solution](../../../src/medium/search_in_rotated_sorted_array.rs)
-- [ ] [Time Based Key-Value Store](https://leetcode.com/problems/time-based-key-value-store/) | Medium | [Solution](../../../src/medium/time_based_key_value_store.rs) | [Problem Description](../../../src/medium/readme.md#981-time-based-key-value-store)
+- [x] [Time Based Key-Value Store](https://leetcode.com/problems/time-based-key-value-store/) | Medium | [Solution](../../../src/medium/time_based_key_value_store.rs) | [Problem Description](../../../src/medium/readme.md#981-time-based-key-value-store)
 - [ ] [Median of Two Sorted Arrays](https://leetcode.com/problems/median-of-two-sorted-arrays/) | Hard | [Solution](../../../src/hard/median_of_two_sorted_arrays.rs)
 
 Category: `Binary Search`
-Created on: 2023-09-21 01:00:00
-Last modified on: 2023-09-30 10:30:00
+Created on: 2023-09-21 01:00
+Last modified on: 2023-10-4 11:50
 Status: In Progress
 Author: [David Bujosa](https://github.com/bujosa)