LRU Cache (Leetcode) [Python 3]

lru_cache.py

class LRUCache:

    def __init__(self, capacity):
        """
        :type capacity: int
        """
        assert(capacity >= 1)
        self.d = {}
        self.first_node = self.last_node = current_node = {}
        for i in range(capacity-1):
            new_node = {'next': current_node}
            current_node['previous'] = new_node
            current_node = self.first_node = new_node
        
    def push(self, new_node):
        new_node['next'] = self.first_node
        self.first_node['previous'] = new_node
        self.first_node = new_node
        
    def remove(self, node):
        if 'previous' in node and 'next' in node:
            node['previous']['next'] = node['next']
            node['next']['previous'] = node['previous']
        elif 'previous' in node:
            self.last_node = node['previous']
            del self.last_node['next']
        elif 'next' in node:
            self.first_node = node['next']
            del self.first_node['previous']
            
        for k in ['previous', 'next']:
            if k in node:
              del node[k]

    def get(self, key):
        """
        :type key: int
        :rtype: int
        """
        if key in self.d:
            if self.first_node is self.last_node:
                return self.d[key]
            node = self.d[key]
            if self.first_node != node:
                self.remove(node)
                self.push(node)
            return node['value']
        else:
            return -1
        

    def put(self, key, value):
        """
        :type key: int
        :type value: int
        :rtype: void
        """
        if self.first_node is self.last_node:
                self.d = {key:value}
                return
        if key in self.d:
            self.get(key)
            self.d[key]['value'] = value
        else:
            if 'key' in self.last_node:
                del self.d[self.last_node['key']]
            new_node = {'key':key, 'value':value}
            self.remove(self.last_node)
            self.push(new_node)
            self.d[key] = new_node


# Your LRUCache object will be instantiated and called as such:
# obj = LRUCache(capacity)
# param_1 = obj.get(key)
# obj.put(key,value)