Python Program for Fibonacci numbers

In this article, we will learn about the solution and approach to solve the given problem statement.

Problem statement −Our task to compute the nth Fibonacci number.

The sequence Fn of Fibonacci numbers is given by the recurrence relation given below

Fn = Fn-1 + Fn-2

with seed values (standard)

F0 = 0 and F1 = 1.

We have two possible solutions to the problem

• Recursive approach
• Dynamic approach

Approach 1 −Recursive Approach

Example

#recursive approach
def Fibonacci(n):
   if n<0:
      print("Fibbonacci can't be computed")
   # First Fibonacci number
   elif n==1:
      return 0
   # Second Fibonacci number
   elif n==2:
      return 1
   else:
      return Fibonacci(n-1)+Fibonacci(n-2)
# main
n=10
print(Fibonacci(n))

Output

34

All the variables are declared in global scope as shown in the image below

Approach 2 −Dynamic Approach

Example

#dynamic approach
Fib_Array = [0,1]

def fibonacci(n):
   if n<0:
      print("Fibbonacci can't be computed")
   elif n<=len(Fib_Array):
      return Fib_Array[n-1]
   else:
      temp = fibonacci(n-1)+fibonacci(n-2)
      Fib_Array.append(temp)
      return temp
# Driver Program
n=10
print(fibonacci(n))

Output

34

All the variables are declared in global scope as shown in the image below

Conclusion

In this article, we learnt about the approach to compute Fibonacci numbers