Lists with multiplication and addition Python

Question

So I have a list that has numbers like [1,2,3,4,5]. What I need the code to be able to multiply and add the numbers so it would look like 1*5 + 2*4 + 3*3 + 4*2 + 5*1. Although these numbers can change based on user input, so it can also look like [1,2,3,4] (1*4+2*3+3*2+4*1)

Also, I'm only allowed to use the operations of the length of list, list accessor, create an empty list, List append.

What have you coded so far? Post an example Of what you have done and people can help. — Hoppo, Jun 10 '20 at 07:41

score 1 · Answer 1 · answered Jun 10 '20 at 07:31

1

If you want the result to be stored in a variable, you could do this:

y=[1,2,3,4,5]
s=len(y)
x=0 #initialize result to 0
for i in range(s):
    x = x + (y[i]*y[s-1-i]) 
    #y[s-1-i] is the the element to be multiplied with y[i]
print(x)

answered Jun 10 '20 at 07:31

Sai

109
8

This solution really just uses basic operation and does the right thing. – AnsFourtyTwo Jun 10 '20 at 07:50

score 0 · Answer 2 · answered Jun 10 '20 at 13:10

0

x=[1,2,3,4,5]
total_sum=sum([a*b for a,b in  zip(x,x[::-1])])

Note: x[::-1] reverses the list

answered Jun 10 '20 at 13:10

Mehul Gupta

1,829
3
17
33

Lists with multiplication and addition Python

2 Answers2