Python Programs on Recursion

Python Programs on Recursion:

1.Write a program using a recursive function to print Fibonacci series up to nth term.       

Ans.

def fibo(n):
    if n==1:
        return 0
    elif n == 2:
        return 1
    else:
        return fibo(n-1)+fibo(n-2)
 
n=int(input("enter no of fibonnaci nos to be printed:"))
for i in range(1,n+1):
    print(fibo(i),end=',')   

2.Write a recursive function to implement binary search algorithm.

Ans.

def binsearch(array,key,low,high):
    if low>high:
        return -1
    mid=int((low+high)/2)
    if key==array[mid]:
        return mid
    elif key <array[mid]:
        high = mid-1
        return binsearch(array,key,low,high)
    else:
        low=mid+1
        return binsearch(array,key,low,high)
 
sortedarray=[10,5,12,15,20,31,34]
item= int(input("enter search item:"))
res=binsearch(sortedarray,item,0,len(sortedarray)-1)
if res>=0:
    print("Found")
else :
    print ("Not Found")

3.Write recursive function to take in a string to print it backwards.

Ans.

def backprint(S):
    n = len(S)
    if n == 0:
        return
    print(S[-1], end = '')
    backprint (S[0:-1])
# _main_
s = input("Enter a string : ")
backprint(s)

4.Write a program to show the use of recursion in calculation of power of a number.

Ans.

def power(a, b) :
     if b == 0 :
             return 1
     else :
             return a * power(a, b-1)
 
n = int (input("Enter number :"))
p = int(input ("Enter power of : "))
result = power(n,p)
print(n, "raised to the power of", p, "is", result)

5.Write recursive code to compute greatest common divisor of two numbers.

Ans.

def gcd(a,b):
    if(b==0):
        return a
    else:
        return gcd(b,a%b)
 
n1=int(input("enter first number:"))
n2=int(input("enter second number:"))
d=gcd(n1,n2)
print("GCD of", n1, "and",n2,"is:",d) 

6.Write recursive code to compute and print sum of squares of numbers. Value of n is passed as parameter.                 

Ans.

def sqsum(n):
    if n==1:
        return 1
    return n*n+sqsum(n-1)
 
n=int(input("enter value of n:"))
print(sqsum(n))n