Generate two output strings depending upon occurrence of character in input string in Python

Given an input string str[], generate two output strings. One of which consists of that character that occurs only once in the input string and the second consists of multi-time occurring characters. Output strings must be sorted. 

Examples:

Input : str = "geeksforgeeks"
Output : String with characters occurring once:
"for".
String with characters occurring multiple times:
"egks"

Input : str = "geekspractice"
Output : String with characters occurring once:
"agikprst"
String with characters occurring multiple times:
"ce"

We have an existing solution for this problem please refer Generate two output strings depending upon occurrence of character in input string link. We can solve this problem quickly in python using Counter(iterable) method. 

The approach is simple,

1. Convert string into dictionary having characters as keys and their frequencies as value using counter() method.
2. Now separate out list of characters having frequency 1 and having frequency more than 1.
3. Sort characters in both lists to get output strings.

Implementation:

Python3

# Function Generate two output strings depending upon
# occurrence of character in input string

from collections import Counter

def generateStrings(input):

    # convert string into dictionary
    # having characters as keys and frequency as value
    freqDict = Counter(input)

    # separate out characters having frequency 1 and more than 1
    freq1 = [ key for (key,count) in freqDict.items() if count==1]
    freqMore1 = [ key for (key,count) in freqDict.items() if count>1]

    # sort lists and concatenate characters
    # with out space to print resultant strings
    freq1.sort()
    freqMore1.sort()

    # print output strings
    print ('String with characters occurring once:')
    print (''.join(freq1))
    print ('String with characters occurring multiple times:')
    print (''.join(freqMore1))

# Driver program
if __name__ == "__main__":
    input = "geeksforgeeks"
    generateStrings(input)

Output

String with characters occurring once:
for
String with characters occurring multiple times:
egks

Time complexity: O(NlogN)
Auxiliary space: O(N)

Method 2: The given program generates two output strings depending upon the occurrence of characters in the input string. Here is an alternative implementation of the same functionality:

Steps:

1. Define the function generateStrings that takes an input string as a parameter.
2. Create two empty lists freq1 and freqMore1 to store characters occurring once and multiple times respectively.
3. Create an empty dictionary char_count to keep track of the count of each character in the input string.
4. Loop through each character in the input string and check if it is already in the dictionary.
5. If the character is not in the dictionary, add it with count 1 and append it to freq1.
6. If the character is already in the dictionary, increment its count and append it to freqMore1.
7. Sort the lists freq1 and freqMore1 in ascending order.
8. Concatenate the characters in the lists without spaces.
9. Print the output strings.
10. In the driver program, define an input string and call the generateStrings function with this string as a parameter.
11. The function will print the two output strings.

Example:

Python3

def generateStrings(input_string):
    # Create two empty lists to store characters occurring once and multiple times
    freq1 = []
    freqMore1 = []

    # Create a dictionary to keep track of the count of each character
    char_count = {}

    # Loop through each character in the input string
    for char in input_string:
        # If the character is not in the dictionary, add it with count 1
        if char not in char_count:
            char_count[char] = 1
            freq1.append(char)
        # If the character is already in the dictionary, increment its count
        else:
            char_count[char] += 1
            freqMore1.append(char)

    # Sort the lists and concatenate the characters without spaces
    freq1.sort()
    freqMore1.sort()

    # Print the output strings
    print('String with characters occurring once:')
    print(''.join(freq1))
    print('String with characters occurring multiple times:')
    print(''.join(freqMore1))


# Driver program
if __name__ == "__main__":
    input_string = "geeksforgeeks"
    generateStrings(input_string)

Output

String with characters occurring once:
efgkors
String with characters occurring multiple times:
eeegks

Time Complexity: O(NlogN), where n is the length of the input string. 
Auxiliary Space: O(N) , where n is the length of the input string.