# 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]

**Visual Presentation:**

**Sample Solution-1:**

**Python Code:**

```
# License: https://bit.ly/3oLErEI
# Define a function named 'test' that takes a list of numbers 'nums' as input
def test(nums):
# Sort the numbers in 'nums' based on the sum of their digits
return sorted(nums, key=lambda n: sum(int(c) for c in str(n) if c != "-"))
# Assign a specific list of numbers 'nums' to the variable
nums = [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
# Print a message indicating the original list of numbers
print("Original list of numbers:", nums)
# Print a message indicating the operation to be performed
print("Sort the numbers of the said list by the sum of their digits:")
# Print the result of the test function applied to 'nums'
print(test(nums))
# Assign another specific list of numbers 'nums' to the variable
nums = [23, 2, 9, 34, 8, 9, 10, 74]
# Print a message indicating the original list of numbers
print("\nOriginal list of numbers:", nums)
# Print a message indicating the operation to be performed
print("Sort the numbers of the said list by the sum of their digits:")
# Print the result of the test function applied to 'nums'
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
# Define a function named 'test' that takes a list of numbers 'nums' as input
def test(nums):
# Create a copy of the original list 'nums' to preserve the original order
unordered = nums.copy()
# Initialize an empty list to store the ordered numbers
ordered = []
# Continue the process until there are no more unordered numbers
while unordered:
# Select the first number in the unordered list as the smallest
smallest = unordered[0]
# Calculate the sum of digits for the current smallest number
s = sum(int(c) for c in str(smallest) if c != "-")
# Iterate through the remaining unordered numbers
for t in unordered:
# Calculate the sum of digits for the current number 't'
t_s = sum(int(c) for c in str(t) if c != "-")
# Compare the sum of digits and update the smallest if needed
if t_s < s:
smallest = t
s = t_s
# Append the smallest number to the ordered list
ordered.append(smallest)
# Remove the smallest number from the unordered list
unordered.remove(smallest)
# Return the final ordered list
return ordered
# Assign a specific list of numbers 'nums' to the variable
nums = [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
# Print a message indicating the original list of numbers
print("Original list of numbers:", nums)
# Print a message indicating the operation to be performed
print("Sort the numbers of the said list by the sum of their digits:")
# Print the result of the test function applied to 'nums'
print(test(nums))
# Assign another specific list of numbers 'nums' to the variable
nums = [23, 2, 9, 34, 8, 9, 10, 74]
# Print a message indicating the original list of numbers
print("\nOriginal list of numbers:", nums)
# Print a message indicating the operation to be performed
print("Sort the numbers of the said list by the sum of their digits:")
# Print the result of the test function applied to 'nums'
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 :**

**Have another way to solve this solution? Contribute your code (and comments) through Disqus.**

**Previous:** Find the largest integer divisor of a number n that is less than n.

**Next:** Determine which triples sum to zero.

**What is the difficulty level of this exercise?**

Test your Programming skills with w3resource's quiz.

**It will be nice if you may share this link in any developer community or anywhere else, from where other developers may find this content. Thanks.**

https://www.w3resource.com/python-exercises/puzzles/python-programming-puzzles-38.php

**Weekly Trends and Language Statistics**- Weekly Trends and Language Statistics