LRUCache(int capacity) Initialize the LRU cache with positive size capacity.
int get(int key) Return the value of the key if the key exists, otherwise return -1.
void put(int key, int value) Update the value of the key if the key exists. Otherwise, add the key-value pair to the cache. If the number of keys exceeds the capacity from this operation, evict the least recently used key.
The functions get and put must each run in O(1) average time complexity.
- implement LRU from scratch ala
- https://github.com/nightisyang/kata-machine/blob/main/src/day2/LRU.ts
- or use a combination of set and map,
- leveraging on the properties of how elements are added in set
- the first element is the last priority
- delete and add key (as element) to push to back of Set, queue
Solution
const LRUCache = function (capacity) {
this.capacity = capacity;
this.cache = new Set();
this.obj = new Map();
};
LRUCache.prototype.get = function (key) {
if (!this.cache.has(key)) {
return -1;
} else {
this.cache.delete(key);
this.cache.add(key);
}
return this.obj.get(key);
};
LRUCache.prototype.put = function (key, value) {
if (!this.cache.has(key)) {
this.cache.add(key);
} else {
this.cache.delete(key);
this.cache.add(key);
}
if (this.cache.size > this.capacity) {
let [first] = this.cache;
this.obj.delete(first);
this.cache.delete(first);
}
this.obj.set(key, value);
};
