📦 Lists & Dictionaries

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

# Ascending order
ascending = sorted(numbers)
print("Ascending:", ascending)

# Descending order
descending = sorted(numbers, reverse=True)
print("Descending:", descending)

# In-place sorting
numbers_copy = numbers.copy()
numbers_copy.sort()
print("In-place sorted:", numbers_copy)

data = [1, 2, 3, 4, 6, 7, 7, 8, 9, 9]

# Method 1: Using set (doesn't preserve order)
unique_set = list(set(data))
print("Using set:", unique_set)

# Method 2: Using dict.fromkeys() (preserves order)
unique_ordered = list(dict.fromkeys(data))
print("Preserving order:", unique_ordered)

# Method 3: Loop approach
unique_loop = []
for item in data:
    if item not in unique_loop:
        unique_loop.append(item)
print("Loop method:", unique_loop)

numbers = [21, 44, 767, 98, 37, 106, 345, 87]

# Method 1: Sort and get second last
sorted_nums = sorted(numbers, reverse=True)
second_largest = sorted_nums[1]
print("Second largest:", second_largest)

# Method 2: Remove max and find new max
nums_copy = numbers.copy()
nums_copy.remove(max(nums_copy))
second = max(nums_copy)
print("Second largest (remove method):", second)

# Method 3: Single pass (efficient)
first = second = float('-inf')
for num in numbers:
    if num > first:
        second = first
        first = num
    elif num > second and num != first:
        second = num
print("Second largest (single pass):", second)

list1 = [21, 44, 767, 98, 37]

# Using built-in functions
maximum = max(list1)
minimum = min(list1)

print(f"Maximum: {maximum}")
print(f"Minimum: {minimum}")

# Manual approach (without built-in)
max_val = list1[0]
min_val = list1[0]
for num in list1:
    if num > max_val:
        max_val = num
    if num < min_val:
        min_val = num
print(f"\nManual - Max: {max_val}, Min: {min_val}")

# Create two dictionaries
dict1 = {'a': 1, 'b': 2, 'c': 3}
dict2 = {'d': 4, 'e': 5, 'f': 6}

# Method 1: Using ** unpacking
merged1 = {**dict1, **dict2}
print("Method 1 (**):", merged1)

# Method 2: Using update()
merged2 = dict1.copy()  # Don't modify original
merged2.update(dict2)
print("Method 2 (update):", merged2)

# Method 3: Using | operator (Python 3.9+)
merged3 = dict1 | dict2
print("Method 3 (|):", merged3)

# Method 1: Dictionary comprehension
squares = {i: i**2 for i in range(1, 6)}
print("Squares:", squares)

# Method 2: Loop approach
squares_loop = {}
for i in range(1, 6):
    squares_loop[i] = i ** 2
print("Squares (loop):", squares_loop)

# Verify
for key, value in squares.items():
    print(f"{key}² = {value}")

car_models = ["Toyota Camry", "Honda Civic", "Ford Mustang", 
              "Chevrolet Silverado", "Nissan Altima"]
car_prices = [2500000, 2200000, 4000000, 3500000, 2300000]

# Using zip() to combine lists into dictionary
car_dict = dict(zip(car_models, car_prices))
print("Car Dictionary:")
for car, price in car_dict.items():
    print(f"  {car}: ₹{price:,}")

# Create grocery dictionary
grocery = {
    "Rice": 850,
    "Milk": 60,
    "Bread": 45,
    "Olive Oil": 750,
    "Cheese": 520
}

# Iterate and check price
print("Grocery List:")
print("-" * 40)
for item, price in grocery.items():
    print(f"{item}: ₹{price}")
    if price > 500:
        print("  ⚠️ This is a costly item!")
print("-" * 40)

# Original grocery dictionary
grocery = {
    "Rice": 850,
    "Milk": 60,
    "Bread": 45,
    "Olive Oil": 750,
    "Cheese": 520
}

# Calculate average price
avg_price = sum(grocery.values()) / len(grocery)
print(f"Average price: ₹{avg_price:.2f}")

# Method 1: Dictionary comprehension (create new dict)
filtered = {item: price for item, price in grocery.items() 
            if price >= avg_price}

print(f"\nItems above average (₹{avg_price:.2f}):")
for item, price in filtered.items():
    print(f"  {item}: ₹{price}")

# Create two sets
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}

# Method 1: Using & operator
common = set1 & set2
print("Common elements (&):", common)

# Method 2: Using intersection()
common2 = set1.intersection(set2)
print("Common elements (method):", common2)

# Function version
def find_common(s1, s2):
    return s1 & s2

result = find_common({10, 20, 30}, {20, 30, 40})
print("Function result:", result)