Python Problems

Question 1

Given a string containing the digits of a number, such as s = “501”, print out the sum of the individual digits. In this case, the output should be 6 = 5 + 0 + 1. Hint: int(‘9’) yields value 9.

Answer 1

Sum digits in string

s = "501"
n = 0
for d in s:
    n += int(d)
print(n)

Question 2

Given a string containing the digits of a number, such as s = “501”, print out the sum of the individual digits. In this case, the output should be 6 = 5 + 0 + 1. Hint: int(‘9’) yields value 9.

Answer 2

Reverse list

A = [1, 9, 2, 4]
"""
example swap (this is a common pattern also):
t = A[3]
A[3] = A[0]
A[0] = t
"""
print(A)
n = len(A)
for i in range(n//2): # 0..n/2-1 (stop halfway!)
    t = A[n-i-1]
    A[n-i-1] = A[i]
    A[i] = t

print(A)