Advanced data structures.

Counter

```python from collections import Counter

Count items fruits = ["apple", "banana", "apple", "orange", "banana", "apple"] count = Counter(fruits)

print(count) # Counter({'apple': 3, 'banana': 2, 'orange': 1}) print(count["apple"]) # 3 print(count.most_common(2)) # [('apple', 3), ('banana', 2)] ```

DefaultDict

```python from collections import defaultdict

No KeyError scores = defaultdict(int) scores["Tom"] += 10 scores["Sarah"] += 20

print(scores) # defaultdict(<class 'int'>, {'Tom': 10, 'Sarah': 20}) ```

Named Tuple

```python from collections import namedtuple

Create Point type Point = namedtuple("Point", ["x", "y"])

p = Point(10, 20) print(p.x) # 10 print(p.y) # 20 ```

Deque

```python from collections import deque

Fast add/remove from both ends queue = deque(["Tom", "Sarah", "Mike"])

queue.append("Alice") # Add right queue.appendleft("Bob") # Add left queue.pop() # Remove right queue.popleft() # Remove left

print(queue) # deque(['Tom', 'Sarah', 'Mike']) ```

Remember

- Counter for counting items - defaultdict to avoid KeyError - deque for fast insertions