Make a Program that reads three numbers and shows them in descending order. Python

Question

Hello, I’m trying to make an algorithm that reads three numbers in Python and delivers them in descending form. The code is right, but I know you can write better only using logic...

a = float(input('Escreva um número: '))
b = float(input('Escreva um número: '))
c = float(input('Escreva um número: '))

if a >= b and a >= c and b >= c:
    print(f'A ordem decrescente é {a} , {b} e {c}')
elif a >= b and a >=c and c >= b:
    print(f'A ordem decrescente é {a} , {c} e {b}')
elif b >= a and b >= c and a >= c:
    print(f'A ordem decrescente é {b} , {a} e {c}')
elif b >= a and b >= c and c >= a:
    print(f'A ordem decrescente é {b} , {c} e {a}')
elif c >= a and c >= b and a >=b:
    print(f'A ordem decrescente é {c} , {a} e {b}')
elif c >= a and c >= b and b >= a:
    print(f'A ordem decrescente é {c} , {b} e {a}')

I wrote this algorithm based on this:

prod_1 = float(input('Valor 1° produto: '))
prod_2 = float(input('Valor 2° produto: '))
prod_3 = float(input('Valor 3° produto: '))

if prod_1 <= prod_2 and prod_1 <= prod_3:
    print('Compre o primeiro produto.')
elif prod_2 <= prod_3:
    print('Compre o segundo produto.')
else:
    print('Compre o terceiro produto')

So I don’t think you need to use lists and something more elaborate, it would just be to exercise logic.

But I don’t think it’s possible to do it without writing a lot of code for a weird task.

Answer 1

Hello, a different way to solve is by using listas and for.

follows an example:

lista = []
qtd = 3
for i in range(qtd):
    elemento = int(input('Digite um numero: '))
    lista.append(elemento)

lista.sort(reverse = True) //ordena os elementos
print(lista)

Answer 2

In general, for any number of elements, the simplest is to place the elements in a list and sort them, as suggested by another answer.

But in the specific case of 3 numbers, and without using lists, you can do so:

if a < c:
    a, c = c, a

if a < b:
    a, b = b, a

if b < c:
    b, c = c, b

print(f'A ordem decrescente é {a}, {b} e {c}')

The first if checks whether a is less than c, and if it is, change their values (a takes on the value of c, and c takes on the value of a). That is, after this if, I know that a will surely be greater or equal to c.

Then I do the same with b, and after the second if I’m sure that a is greater than or equal to b. And as the first if assured that a is greater than or equal to c, so at this point I already know that a is the greatest of all.

Then all that remains is to check whether b is less than c, and if so, I change their values. So, after the third if, for sure b shall be greater than or equal to c.

So at the end of these three if's, I know that a, b and c will be in unbelieving order.