Sorting & Searching

Built-in sorting:

numbers = [3, 1, 4, 1, 5, 9, 2, 6]
numbers.sort()               # in-place
sorted_copy = sorted(numbers) # new list
reversed_list = sorted(numbers, reverse=True)

Sorting with key:

words = ["banana", "apple", "cherry", "date"]
words.sort(key=len)          # sort by length
words.sort(key=str.lower)    # case-insensitive

people = [("Alice", 30), ("Bob", 25), ("Charlie", 35)]
people.sort(key=lambda p: p[1])  # sort by age

Searching:

"banana" in words            # True
words.index("apple")         # returns position
words.count("apple")         # count occurrences

Binary search (for sorted lists):

import bisect
sorted_nums = [1, 3, 5, 7, 9]
position = bisect.bisect_left(sorted_nums, 5)  # 2

Performance: Python's sort uses Timsort — O(n log n) worst case. The in operator is O(n) for lists, O(1) for sets and dicts.

Reference:

Wikipedia: Sorting Algorithm

https://en.wikipedia.org/wiki/Sorting_algorithm