Program to find the nth Fibonacci number using Python

by | Jan 31, 2021 | Python Programs

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Introduction

In this section, we will understand the python code to print nth Fibonacci number of the given number. The expression for Fibonacci number is:

F(n) = F(n-1) + F(n-2)

Given, F(0) = 0 and F(1) = 1

Program to find the nth Fibonacci number using Python

Program

Program 1: Recursion

def fibo(m):

    if m < 0:

        print("Please enter the valid input!")

    elif m == 1:

# F(0) is 0

        return 0

    elif m == 2:

# F(1) is 1

        return 1

    else:

# Recurrence relation

        return fibo(m-1)+fibo(m-2)

       

n = int(input("Please enter the integer value to find nth Fibonacci number: "))

print("The Fibonacci number corresponding to", n, "is", fibo(n))

 

Output

Program to find the nth Fibonacci number using Python Output 1

Program 2: Dynamic programming

def fibo(m):

    f_array = [0, 1]

    if m < 0:

        print("Please enter the valid input!")

    elif m <= len(f_array):

        return f_array[m-1]

    else:

        temp = fibo(m-1) + fibo(m-2)

        f_array.append(temp)

        return temp

       

n = int(input("Please enter the integer value to find nth Fibonacci number: "))

print("The Fibonacci number corresponding to", n, "is", fibo(n))

 

 

Output:

Program to find the nth Fibonacci number using Python Output 2

Explanation

In the above program, we have created a variable n to take the positive integer input from the user. The fibo() function calculates the nth Fibonacci number by relation F(n-1) + F(n-2).

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