Python – Sort by Factor count
Given element list, sort by factor count of each element.
Input : test_list = [12, 100, 22]
Output : [22, 12, 100]
Explanation : 3, 5, 8 factors respectively of elements.Input : test_list = [6, 11]
Output : [11, 6]
Explanation : 1, 4 factors respectively of elements.
Method #1 : Using sort() + len() + list comprehension
In this, we perform task of sorting using sort(), and len() and list comprehension is used for task of getting the count of factors.
Python3
# Python3 code to demonstrate working of# Sort by Factor count# Using sort() + len() + list comprehensiondef factor_count(ele): # getting factors count return len([ele for idx in range(1, ele) if ele % idx == 0])# initializing listtest_list = [12, 100, 360, 22, 200]# printing original listprint("The original list is : " + str(test_list))# performing sorttest_list.sort(key=factor_count)# printing resultprint("Sorted List : " + str(test_list)) |
Output:
The original list is : [12, 100, 360, 22, 200] Sorted List : [22, 12, 100, 200, 360]
Time Complexity: O(nlogn) where n is the number of elements in the list “test_list”.
Auxiliary Space: O(1) additional space is not needed
Method #2 : Using lambda + sorted() + len()
In this, task of sorting is done using sorted(), and lambda function is used to feed to sorted to get factors.
Python3
# Python3 code to demonstrate working of# Sort by Factor count# Using lambda + sorted() + len()# initializing listtest_list = [12, 100, 360, 22, 200]# printing original listprint("The original list is : " + str(test_list))# performing sort using sorted(), lambda getting factorsres = sorted(test_list, key=lambda ele: len( [ele for idx in range(1, ele) if ele % idx == 0]))# printing resultprint("Sorted List : " + str(res)) |
Output:
The original list is : [12, 100, 360, 22, 200] Sorted List : [22, 12, 100, 200, 360]
Method #3: Using a dictionary to store factor counts and sort by value
Algorithm:
Define an empty dictionary factor_counts.
Iterate over the elements of the input list test_list and for each element ele:
a. Define a variable count to store the number of factors of ele.
b. Iterate over the range from 1 to ele, inclusive, and increment count for each factor of ele.
c. Add a key-value pair to factor_counts with key ele and value count.
Sort test_list by factor count using the factor_counts dictionary. To do this, pass a lambda function to the sorted() function as the key parameter, which returns the value of the corresponding key-value pair in factor_counts for each element in test_list.
Return the sorted list.
Python3
# Python3 code to demonstrate working of# Sort by Factor count# Using a dictionary to store factor counts and sort by value# initializing listtest_list = [12, 100, 360, 22, 200]# printing original listprint("The original list is : " + str(test_list))# defining an empty dictionary to store factor countsfactor_counts = {}# iterating over the elements of the input list and storing factor counts in the dictionaryfor ele in test_list: count = 0 for idx in range(1, ele + 1): if ele % idx == 0: count += 1 factor_counts[ele] = count# sorting the list by factor count using the dictionaryres = sorted(test_list, key=lambda ele: factor_counts[ele])# printing resultprint("Sorted List : " + str(res)) |
The original list is : [12, 100, 360, 22, 200] Sorted List : [22, 12, 100, 200, 360]
Time complexity: O(n^2), where n is the length of the input list.
Auxiliary space: O(n), where n is the length of the input list.
