# Python: Sort the numbers by the sum of their digits

## Python Programming Puzzles: Exercise-38 with Solution

Write a Python program to sort the numbers in a given list by the sum of their digits.

Input: [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] Output: [10, 11, 20, 12, 13, 14, 15, 16, 17, 18, 19] Input: [23, 2, 9, 34, 8, 9, 10, 74] Output: [10, 2, 23, 34, 8, 9, 9, 74]

**Pictorial Presentation:**

**Sample Solution-1:**

**Python Code:**

```
#License: https://bit.ly/3oLErEI
def test(nums):
return sorted(nums, key=lambda n: sum(int(c) for c in str(n) if c != "-"))
nums = [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
print("Original list of numbers:",nums)
print("Sort the numbers of the said list by the sum of their digits:")
print(test(nums))
nums = [23,2,9,34,8,9,10,74]
print("\nOriginal list of numbers:",nums)
print("Sort the numbers of the said list by the sum of their digits:")
print(test(nums))
```

Sample Output:

Original list of numbers: [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] Sort the numbers of the said list by the sum of their digits: [10, 11, 20, 12, 13, 14, 15, 16, 17, 18, 19] Original list of numbers: [23, 2, 9, 34, 8, 9, 10, 74] Sort the numbers of the said list by the sum of their digits: [10, 2, 23, 34, 8, 9, 9, 74]

**Flowchart:**

**Sample Solution-2:**

**Python Code:**

```
#License: https://bit.ly/3oLErEI
def test(nums):
unordered = nums.copy()
ordered = []
while unordered:
# The number that comes first, since the list is sorted by the primes
smallest = unordered[0]
s = sum(int(c) for c in str(smallest) if c != "-")
for t in unordered:
t_s = sum(int(c) for c in str(t) if c != "-")
if t_s < s:
smallest = t
s = t_s
ordered.append(smallest)
unordered.remove(smallest)
return ordered
nums = [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
print("Original list of numbers:",nums)
print("Sort the numbers of the said list by the sum of their digits:")
print(test(nums))
nums = [23,2,9,34,8,9,10,74]
print("\nOriginal list of numbers:",nums)
print("Sort the numbers of the said list by the sum of their digits:")
print(test(nums))
```

Sample Output:

Original list of numbers: [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] Sort the numbers of the said list by the sum of their digits: [10, 11, 20, 12, 13, 14, 15, 16, 17, 18, 19] Original list of numbers: [23, 2, 9, 34, 8, 9, 10, 74] Sort the numbers of the said list by the sum of their digits: [10, 2, 23, 34, 8, 9, 9, 74]

**Flowchart:**

**Python Code Editor :**

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