Python program to find the nth Fibonacci Number

You can find the nth Fibonacci number in Python using various methods, including recursion, iterative loops, and dynamic programming. Here are a few examples:

1. Using Recursion: The Fibonacci sequence can be defined recursively as follows:

   def fibonacci_recursive(n):
       if n <= 0:
           return 0
       elif n == 1:
           return 1
       else:
           return fibonacci_recursive(n - 1) + fibonacci_recursive(n - 2)

   # Find the nth Fibonacci number
   n = 10  # Change this to the desired value of n
   nth_fibonacci = fibonacci_recursive(n)
   print(f"The {n}th Fibonacci number is {nth_fibonacci}")

Be cautious when using recursion for large values of n as it can lead to a significant performance hit due to repeated calculations.

2. Using Iteration: You can calculate the nth Fibonacci number iteratively using a loop:

   def fibonacci_iterative(n):
       if n <= 0:
           return 0
       elif n == 1:
           return 1
       else:
           a, b = 0, 1
           for _ in range(2, n + 1):
               a, b = b, a + b
           return b

   # Find the nth Fibonacci number
   n = 10  # Change this to the desired value of n
   nth_fibonacci = fibonacci_iterative(n)
   print(f"The {n}th Fibonacci number is {nth_fibonacci}")

This iterative approach is more efficient than the recursive one for large n values.

3. Using Memoization (Dynamic Programming): You can optimize the recursive approach using memoization to store and reuse previously calculated Fibonacci numbers:

   def fibonacci_memoization(n, memo={}):
       if n <= 0:
           return 0
       elif n == 1:
           return 1
       elif n in memo:
           return memo[n]
       else:
           memo[n] = fibonacci_memoization(n - 1, memo) + fibonacci_memoization(n - 2, memo)
           return memo[n]

   # Find the nth Fibonacci number
   n = 10  # Change this to the desired value of n
   nth_fibonacci = fibonacci_memoization(n)
   print(f"The {n}th Fibonacci number is {nth_fibonacci}")

Memoization improves the performance of the recursive solution by avoiding redundant calculations.

Choose the method that best suits your needs, depending on the desired value of n and the efficiency requirements of your application.