What are some examples of memoization in Python?

What are some examples of memoization in Python?

Memoization is an optimization technique used to speed up function calls by storing previously computed results. A common example in Python is using a dictionary to cache results of a recursive function, like calculating Fibonacci numbers.

Can you show me a code example?

Sure! Here's a simple example of memoization for the Fibonacci sequence:

memo = {}

def fib(n):
    if n in memo:
        return memo[n]
    if n <= 1:
        return n
    memo[n] = fib(n-1) + fib(n-2)
    return memo[n]

How does this improve performance?

Without memoization, the Fibonacci function has exponential time complexity due to repeated calculations. With memoization, it reduces to linear time complexity, as each number is calculated only once.

Are there any built-in libraries for memoization in Python?

Yes, Python's functools module has a lru_cache decorator that can be used for memoization. It automatically caches results of function calls.