Method Put

lru_cache_146/solution.go:28–69

(key int, value int)

}

func (cache *LRUCache) Put(key int, value int) {
	existingNode, ok := cache.keyMap[key]
	if ok {
		existingNode.value = value
		cache.bringNodeToFront(existingNode)
		return
	}

	node := &LRUNode{
		key:   key,
		value: value,
	}
	cache.keyMap[key] = node

	// no need to evict, so place in front of list
	if cache.load < cache.capacity {
		if cache.front == nil && cache.rear == nil {
			cache.front = node
			cache.rear = node
		} else {
			cache.insertInFront(node)
		}

		cache.load = cache.load + 1
		return
	}

	// load is equal to capacity, so need to evict the LRU
	evicted := cache.keyMap[cache.rear.key]
	delete(cache.keyMap, cache.rear.key)

	// a single node is to be evicted
	if evicted.next == nil && evicted.prev == nil {
		cache.front = node
		cache.rear = node
		return
	}

	cache.rear = cache.rear.prev
	cache.rear.next = nil
	cache.insertInFront(node)
}

func (cache *LRUCache) Get(key int) int {
	node, ok := cache.keyMap[key]