Data Structure: list, tuple, dict, set

cart = ["চাল", "ডাল", "তেল"]

cart.append("লবণ")          # শেষে যোগ
cart.insert(0, "চিনি")      # নির্দিষ্ট জায়গায় যোগ
cart.extend(["আটা", "ডিম"])  # অনেকগুলো একসাথে
removed = cart.pop()         # শেষেরটা সরাও আর ফেরত দাও
cart.remove("তেল")           # value দিয়ে সরাও (প্রথম যেটা মেলে)

print(len(cart))             # কতগুলো
print("ডাল" in cart)         # আছে কিনা: True
print(cart[0], cart[-1])     # প্রথম আর শেষ
print(cart[1:3])             # slicing

# sort
prices = [550, 120, 999, 75]
prices.sort()                # নিজেই বদলে যায়: [75, 120, 550, 999]
top = sorted(prices, reverse=True)  # নতুন list দেয়, পুরনোটা ঠিক থাকে

products = [
    {"name": "Headphone", "price": 2500, "rating": 4.2},
    {"name": "Mouse", "price": 650, "rating": 4.7},
    {"name": "Keyboard", "price": 1800, "rating": 4.5},
]

cheap_first = sorted(products, key=lambda p: p["price"])
best_first = sorted(products, key=lambda p: p["rating"], reverse=True)

for p in best_first:
    print(p["name"], p["rating"])

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

squares = [n * n for n in numbers]               # map
evens = [n for n in numbers if n % 2 == 0]       # where/filter
even_squares = [n * n for n in numbers if n % 2 == 0]

names = ["  rahim ", "KARIM", "Sara  "]
clean = [n.strip().title() for n in names]       # ['Rahim', 'Karim', 'Sara']

location = (23.8103, 90.4125)     # ঢাকার latitude, longitude
lat, lng = location               # unpacking
print(lat)

# function থেকে একাধিক value ফেরত দেওয়া আসলে tuple ফেরত দেওয়া
def min_max(values: list[int]) -> tuple[int, int]:
    return min(values), max(values)

low, high = min_max([5, 2, 9, 1])

first, *rest = [10, 20, 30, 40]      # first=10, rest=[20, 30, 40]
a, b = 1, 2
a, b = b, a                          # swap, temp variable ছাড়াই

user = {
    "id": 101,
    "name": "Nusrat",
    "city": "Chattogram",
    "skills": ["Flutter", "Python"],
}

print(user["name"])                  # Nusrat
print(user.get("phone"))             # None, error দেয় না
print(user.get("phone", "নেই"))      # default value

user["phone"] = "01700000000"        # যোগ বা বদল
del user["city"]                     # মুছে ফেলা

for key, value in user.items():
    print(f"{key} → {value}")

print(list(user.keys()))
print("name" in user)                # key আছে কিনা: True

prices = {"আম": 120, "কলা": 60, "আপেল": 280}
with_vat = {item: round(p * 1.15) for item, p in prices.items()}
cheap = {item: p for item, p in prices.items() if p < 150}

visitors = ["ali", "sara", "ali", "rafi", "sara"]
unique = set(visitors)          # {'ali', 'sara', 'rafi'}
print(len(unique))              # 3 জন আলাদা মানুষ

flutter_devs = {"ali", "sara", "nila"}
python_devs = {"sara", "rafi", "nila"}

print(flutter_devs & python_devs)   # দুটোই জানে: {'sara', 'nila'}
print(flutter_devs | python_devs)   # যেকোনো একটা জানে
print(flutter_devs - python_devs)   # শুধু Flutter: {'ali'}

import time

big_list = list(range(1_000_000))
big_set = set(big_list)

start = time.perf_counter()
for _ in range(1000):
    999_999 in big_list
print(f"list: {time.perf_counter() - start:.3f} সেকেন্ড")

start = time.perf_counter()
for _ in range(1000):
    999_999 in big_set
print(f"set:  {time.perf_counter() - start:.6f} সেকেন্ড")

a = [1, 2, 3]
b = a
b.append(4)
print(a)        # [1, 2, 3, 4]  😮

# আলাদা copy চাইলে
c = a.copy()    # বা list(a) বা a[:]
c.append(5)
print(a)        # [1, 2, 3, 4]  ঠিক আছে

# ভেতরে list থাকলে copy() যথেষ্ট না (shallow copy)
import copy
matrix = [[1, 2], [3, 4]]
shallow = matrix.copy()
shallow[0].append(99)
print(matrix)   # [[1, 2, 99], [3, 4]]  ভেতরেরটা তখনও share হচ্ছে
deep = copy.deepcopy(matrix)  # পুরোপুরি আলাদা

from collections import Counter, defaultdict, deque

# Counter: গোনা
words = "আম জাম আম কাঁঠাল আম জাম".split()
count = Counter(words)
print(count.most_common(2))          # [('আম', 3), ('জাম', 2)]

# defaultdict: key না থাকলে নিজে default বানায়
orders_by_city = defaultdict(list)
orders = [("Dhaka", 101), ("Sylhet", 102), ("Dhaka", 103)]
for city, order_id in orders:
    orders_by_city[city].append(order_id)   # আগে key আছে কিনা check লাগে না
print(dict(orders_by_city))          # {'Dhaka': [101, 103], 'Sylhet': [102]}

# deque: দুই দিক থেকেই দ্রুত যোগ/বাদ (queue এর জন্য)
queue = deque()
queue.append("order-1")
queue.append("order-2")
first = queue.popleft()               # list.pop(0) এর চেয়ে অনেক দ্রুত