題目(5kyu)：

My friend John and I are members of the "Fat to Fit Club (FFC)". John is worried >because each month a list with the weights of members is published and each month he is >the last on the list which means he is the heaviest.

I am the one who establishes the list so I told him: "Don't worry any more, I will >modify the order of the list". It was decided to attribute a "weight" to numbers. The >weight of a number will be from now on the sum of its digits.

For example 99 will have "weight" 18, 100 will have "weight" 1 so in the list 100 will >come before 99.

Given a string with the weights of FFC members in normal order can you give this string >ordered by "weights" of these numbers?

Example:
"56 65 74 100 99 68 86 180 90" ordered by numbers weights becomes:

"100 180 90 56 65 74 68 86 99"
When two numbers have the same "weight", let us class them as if they were strings >>。>(alphabetical ordering) and not numbers:

180 is before 90 since, having the same "weight" (9), it comes before as a string.
All numbers in the list are positive numbers and the list can be empty.

Notes
it may happen that the input string have leading, trailing whitespaces and more than a >unique whitespace between two consecutive numbers
For C: The result is freed.

解題思路

題目理解：設計一函式將字串strng內數字，依"權重"來排序，其定義一個數字的權重為該數的所有位數數字相加，例：
1810 >> 1+8+1+0 = 10
依權重將數字由小排到大，若遇到權重相同時，將數字以字符串形式做排序比較。可以理解為當數字以字符串形式去做sorted時會獲得的順序，例：

print(sorted([180,90])) #返還[90, 180]
print(sorted(["180","90"])) #返還['180', '90']

故需遵從以上兩點，將strng重新排序後以字串形式輸出。
示例如下：

def order_weight(strng):
    "將strng內數字依權重規則重新排列後輸出成字串"
    #將字串內數字切割入列表arr存儲
    arr = strng.split(" ")
    lst = []
    #將arr內數字依（權重weight,字串num）形式重新存成列表lst
    for nb in arr:
        lst.append((sum([int(i) for i in nb]),nb))
    reslut = ""
    #sorted()時會先從每個元組內的第一個元素做排序，故會先依int型態的權重做排序
    #若遇相同結果時，sorted()會從該元組的第二元素依其string型態的數字本身做排序
    sort_lst = sorted(lst)
    #故此時sort_lst中的num順序以符合題目要求
    for weight,num in sort_lst:
        reslut += num
        #如果當前遞迴並非最後一組元組，皆需加上" "
        if (weight,num) != sort_lst[-1]:
            reslut += " "
    return reslut