Design and implement a data structure for a cache, which has the following functions: get(key) Return the value associated with the specified key if it exists in the cache, else return -1 . put(key, value, weight) Associate value with key in the cache, such that value might be later retrieved by get(key) . Cache has a fixed capacity, and when such capacity is reached, key with the least score must be invalidated until the number of key s falls within cache capacity. The score is calculated as follows: - weight ∕ [ln(current_time - last_accessed_time + 1) + 1] Implementation of the cache should be optimized on the time complexity of get(key) .

type Cache struct {
    cache map[int]CacheNode
    capacity int
}

type CacheNode struct {
    key int
    value int
    weight int
}