Python | Largest number possible from list of given numbers

Given a list of numbers, the task is to find the largest number possible from the elements given in the list.

This is one of the problems that is essential in 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 reverse sort of list indices converted into string and lambda functions handles the conversion and iteration operation.

# Python code to demonstrate
# largest possible number in list
# using sorted() + lambda
from functools import cmp_to_key

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

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

# using sorted() + lambda
# largest possible number in list
res = sorted(test_list, key = cmp_to_key(lambda i, j: -1
                if str(j) + str(i) < str(i) + str(j) else 1))

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

Output:

The original list is : [23, 65, 98, 3, 4]
The largest possible number : 98654323

Method #2 : Using itertools.permutation() + join() + max()
The itertools.permutation can be used to get possible permutation and max function chooses the maximum of it after being converted to integer as a result of joined output as given by join function.

# Python3 code to demonstrate
# largest possible number in list
# using itertools.permutation() + join() + max()
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() + max()
# largest possible number in list
res = int(max((''.join(i) for i in permutations(str(i)
                     for i in test_list)), key = int))

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

Output:

The original list is : [23, 65, 98, 3, 4]
The largest possible number : 98654323