Day 14 - Python

Problem Statement: Unique Substrings

You are given a string, s. Your task is to find and print all unique substrings of length greater than 1 in alphabetical order of increasing length.

Input Format:

A single line containing a string, s, consisting of lowercase English letters only.

Output Format:

Print the number of unique substrings followed by the substrings themselves, each on a new line.

Constraints:

2 ≤ Length of s ≤ 1000

Sample Input:

msdhoni

Sample Output:

21

dh

dho

dhon

dhoni

ho

hon

honi

ms

msd

msdh

msdho

msdhon

msdhoni

ni

on

oni

sd

sdh

sdho

sdhon

sdhoni

Explanation:

In the given string "msdhoni", the unique substrings of length greater than 1 are printed in alphabetical order of increasing length.

Test Cases:

code

6

co

cod

code

de

od

ode 

csk

3

cs

csk

sk 

SOLUTION:

def unique_substrings(s):

    substrings = set()

    n = len(s)

    for length in range(2, n + 1): 

        for i in range(n - length + 1):

            res = s[i:i + length]

            substrings.add(res)

    substrings = sorted(substrings)  

    print(len(substrings))

    print()

    for i in substrings:

        print(i)

s = input()

unique_substrings(s)

Insights:

• The function utilizes a set substrings to store unique substrings. This ensures that duplicate substrings are not included in the final output.
• It employs nested loops to iterate over all possible substrings of different lengths. The outer loop iterates over the lengths of substrings, while the inner loop generates substrings of the current length.
• The range for the outer loop starts from 2 and goes up to n + 1, where n is the length of the input string s. This ensures that substrings of at least length 2 are considered.
• Substrings are generated using slicing s[i:i + length], where i is the starting index and length is the current length being considered.
• Each generated substring is added to the substrings set, ensuring uniqueness.
• After generating all unique substrings, the function sorts them alphabetically using the sorted function. This step ensures that the substrings are printed in alphabetical order.
• The function prints the count of unique substrings first, indicating the total number of unique substrings found. Finally, it iterates over the sorted substrings and prints each substring on a new line.

Happy Coding! :)