Reading in a positive int and transform every digit of that number in an even-odd way-CodePudding

So what I need to do is read in a number and transform every digit.

add 2 to an odd digit
subtract 3 from an even digit (watch out for negative numbers!)
zero stays 0

input
14502

wanted output
31701
Current output
14504

Below is what I have for now, I can read every digit in a for loop but I don't know how to transorm them one by one.

num = int(input("Enter a number:"))


for digit in str(num):
print(digit)
if (num % 2)==0:
    print(num   2)
else:   
    print(num - 3)

ALSO NO IMPORTS

CodePudding user response：

num = input("Enter a number:")
new_num = []
single_number = ''
for digit in num:
    digit = int(digit)
    if digit == 0:
        new_num.append(digit)
    elif (digit % 2)!=0:
        digit = digit 2
        new_num.append(digit)
    elif (digit % 2)==0:
        digit = digit-3
        if digit>=0:
            new_num.append(digit)
        else:
            digit = digit*(-1)
            new_num.append(digit)
print(new_num)

# for single int instead of array
for digit in new_num:
    digit = str(digit)
    single_number = single_number digit
print(single_number)

new_number is array of digits single_number is the final number you want.

CodePudding user response：

is your code missing the indent after the for loop? I know that may not solve the question but is that another issue with your code or just a formatting issue here on stack?

num = int(input("Enter a number:"))

    for digit in str(num):
        print(digit)
        if (num % 2)==0:
            print(num   2)
        else:   
            print(num - 3)

CodePudding user response：

num = int(input("Enter a number:"))
print(len(str(num)))
finaloutput = []
for i in range(len(str(num))):
    digit = num
    if digit%2==0:
        if digit - 3 < 0:
            digit = 0
        else:
            digit = digit - 3
    else:
        digit = digit   2
    finaloutput.append(digit)
    num = num //10
print(finaloutput)
string=""
for i in range(len(finaloutput)):
    string = string   str(finaloutput[i])
print(string[::-1])

Might be a big scuffed but gets the job done. Substract 3 from even, add 2 to odds, and watch for zeros.

output:

Enter a number:14502
5
[0, 0, 7, 1, 3]
31700

I put it so if an even number sub 3 is less than zero it jus stays zero, bc thats how I understood it. You can easily modify the code to suit your need and in accordance with your task or whatever

CodePudding user response：

Try:

num = 9876543210

l = [int(c) for c in str(s)]

l = [min(c, 7)   2 if c % 2 else max(c, 4) - 3 if c != 0 else c for c in l]

out = int(''.join(str(c) for c in l))

Output:

>>> out
9593715130

Details:

9 -> 9 (else 12)
8 -> 5 (-3)
7 -> 9 (else 10)
6 -> 3 (-3)
5 -> 7 ( 2)
4 -> 1 (-3)
3 -> 5 ( 2)
2 -> 1 (else -1)
1 -> 3 ( 2)
0 -> 0 (do nothing)

CodePudding user response：

A simple implementation based on your solution. It can only handle integers though. And there is one case which you have not specified which is

what to do when the digit is 9? As 9 2 = 11 and 11 is not a digit but could well be what you want in your algorithm?

In this implementation 9 is turned to 1.

def calc_on_digits(num: str):
    result: str = ""

    for digit in num:
        digit = int(digit)
        if digit == 0:
            result  = "0"
            continue
        if digit % 2 == 0:
            # in case it get negative take the absolute value
            digit = abs(digit - 3)
        else:
            digit  = 2
            # in case its 9 the result would be 11 -> make it one
            digit = digit % 10
        result  = str(digit)
    return result

# string in this implementation can only contain valid integer values
print(calc_on_digits("14502"))

CodePudding user response：

You cannot calculate modulo from string. Also you have to perform the comparison per digit, not for the whole number.

num = input("Enter a number:")  # no need to cast to int just to transform back to str below

new_number = ""
for digit in num:
    digit = int(digit)
    print(digit)
    if (digit % 2) = 0:
        tmp = digit   2
        if tmp >= 10:
            tmp = 0
    else:
        tmp = digit - 3
        if tmp < 0:
            tmp = 0
    new_number  = str(tmp)