Python中特定方式的数字总和

Question

I'm looking for a code that runs, ie:

    int(input) = 2565

Printed Output should be like:

    2 + 5 + 6 + 5  = 18 = 1 + 8 = 9

I wrote the code that gives final answer "9". But I couldn't managed to write it with every digit separated "+" sign. Assuming that I need to use while loop but how can I write the code so it will be like the output above?

Answer 1

You can use something like this:

def sum_of_digits(s):
    if s < 10:
        return s
    return sum_of_digits(sum(int(c) for c in str(s)))
    
> sum_of_digits(2565)
9

It recursively checks if the numerical value is less than 10. If it does, it returns this value. If not, it adds the digits, then recursively calls itself on the result.

Edit

To print out the steps as it goes along, you could do something like this:

def sum_of_digits(s):
    if s < 10:
        print(s)
        return s
    print(' + '.join(c for c in str(s)) + ' = ')
    return sum_of_digits(sum(int(c) for c in str(s)))

Answer 2

First, initiate an empty string output_str .
With a while loop which contniues when our integer is > 9:

1. [s for s in str(x)] would create a list of the digits (as strings) of our integer. It's called a list comprehension , is very useful, and my advice is to read a bit about it.
2. With " + ".join() we create a string with " + " between the digits. Add this string at the end of output_str .
3. Add " = " to the end of output_str .
4. Calculate the sum of the digits (we cannot use sum(lst_of_digits) because it's a list of strings. sum([int(s) for s in lst_of_digits]) converts the string list into an inter list, which can be summed using sum() ). Store the sum into x .
5. Add the new x + " = " to output_string .

At the end of the string, we have a redundant " = " (because the last (5) was not needed), let's just remove the last 3 chars ( = ) from it.

x = 2565
output_str = ""
while x > 9:
    lst_of_digits = [s for s in str(x)]
    output_str += " + ".join(lst_of_digits)
    output_str += " = "
    x = sum([int(s) for s in lst_of_digits])
    output_str += f"{x} = "
output_str = output_str[:-3]

outputs:
output_str = '2 + 5 + 6 + 5 = 18 = 1 + 8 = 9'

Answer 3

You can play around with the end keyword argument of the print function which is the last character/string that print will put after all of its arguments are, well, printed, by default is "\\n" but it can be change to your desire.

And the .join method from string which put the given string between the given list/iterable of strings to get the desire result:

>>> " + ".join("123")
'1 + 2 + 3'
>>> 

Mixing it all together:

def sum_digit(n):
    s = sum(map(int,str(n)))
    print(" + ".join(str(n)),"=",s, end="")
    if s<10:
        print()
        return s
    else:
        print(" = ",end="")
        return sum_digit(s)

Here we first get the sum of the digit on s , and print it as desire, with end="" print will not go to the next line which is necessary for the recursive step, then we check if done, and in that case print a new empty line if not we print an additional = to tie it for the next recursive step

>>> sum_digit(2565)
2 + 5 + 6 + 5 = 18 = 1 + 8 = 9
9
>>> 

This can be easily be modify to just return the accumulated string by adding an extra argument or to be iterative but I leave those as exercise for the reader :)

Answer 4

I am a noob but this should do what you want.

Cheers, Guglielmo

import math
import sys

def sumdigits(number):

    digits = []
    for i in range( int(math.log10(number)) + 1):
      digits.append(int(number%10))
      number = number/10

    digits.reverse()
    string = ''
    thesum = 0
    for i,x in enumerate(digits):
      string += str(x)
      thesum += x
      if i != len(digits)-1: string += ' + '
      else: string += ' = '

    if thesum > 10:
      return string,thesum,int(math.log10(number))+1
    else:
      return string,thesum,0


def main():

    number = float(sys.argv[1])
    finalstring = ''

    string,thesum,order = sumdigits(number)
    finalstring += string
    finalstring += str(thesum)
    
    while order > 0:
      finalstring += ' = '
      string,thesum,order = sumdigits(thesum)

      finalstring += string
      finalstring += str(thesum)


    print 'myinput = ',int(number)
    print 'Output = ',finalstring

if __name__ == "__main__":
    main()