Python – Smallest integer possible from combination of list elements

Given a list of integers, the task is to get smallest integer possible from the combination of list elements. This is one of the problems that is essential in a competitive point of view and this article discusses various shorthands to solve this problem in Python. Let’s discuss certain ways in which this problem can be solved.

Method #1 : Using sorted() + lambda
The combination of the above function can be used to perform this task. The sorted function performs the sort of list indices converted into string and lambda functions handle the conversion and iteration operation.

# Python code to demonstrate
# Smallest number from list
# using sorted() + lambda
import functools

# initializing list
test_list = [23, 65, 98, 3, 4]

# printing original list
print ("The original list is : " + str(test_list))

# lambda for custom operation
custom = lambda i, j: -1 if str(j) + str(i) > str(i) + str(j) else 1

# using sorted() + custom function
# Smallest number from list
res = sorted(test_list, key = functools.cmp_to_key(custom))


# printing result
print ("The smallest possible number : " + "".join(map(str, res)))

Output :

The original list is : [23, 65, 98, 3, 4]
The smallest possible number : 23346598

Method #2 : Using itertools.permutation() + join() + min()

The itertools.permutation can be used to get possible permutation and min function chooses the minimum of it after being converted to integer as a result of joined output as given by join function.

# Python3 code to demonstrate
# Smallest number from list
# using itertools.permutation() + join() + min()
from itertools import permutations

# initializing list
test_list = [23, 65, 98, 3, 4]

# printing original list
print ("The original list is : " + str(test_list))

# using itertools.permutation() + join() + min()
# Smallest number from list
res = int(min((''.join(i) for i in permutations(str(i)
                     for i in test_list)), key = int))

# printing result
print ("The smallest possible number : " + str(res))

Output :

The original list is : [23, 65, 98, 3, 4]
The smallest possible number : 23346598