PMCA Saturday 18:30 Python Homework 22.03.19.

20 Mar PMCA Saturday 18:30 Python Homework 22.03.19.

Question:

Use the recursion we have learn in the class, please try to create a function to recursively calculate the total of 1 + 2 + …. (n-2) + (n-1) + n

def total(n):
    # please write you program below

total(int(input('Please enter a number:')))

Class Notes:

All recursive algorithms must obey three important laws:

1. A recursive algorithm must have a base case.
2. A recursive algorithm must change its state and move toward the base case.
3. A recursive algorithm must call itself, recursively.

Sample program:

def listsum(numList):
    if len(numList) == 1:
        return numList[0]
    else:
        return numList[0] + listsum(numList[1:])

print(listsum([1,3,5,7,9]))