HackerRank Python Solution - Strings - Merge the Tools!

Consider the following:

• A string, s, of length n where s=c₀c₁...c_n-1.
• An integer, k, where k is a factor of n.

We can split s into n/k substrings where each substring, t_i, consists of a contiguous block of k characters in s. Then, use each t_i to create string u_i such that:

• The characters in u_i are a subsequence of the characters in t_i.
• Any repeat occurrence of a character is removed from the string such that each character in u_i occurs exactly once. In other words, if the character at some index j in t_i occurs at a previous index < j in t_i, then do not include the character in string u_i.

Given s and k, print n/k lines where each line i denotes string u_i.

Example:

• s = 'AAABCADDE'
• k = 3
• There are three substrings of length 3 to consider: 'AAA', 'BCA' and 'DDE'. The first substring is all 'A' characters, so u₁='A'. The second substring has all distinct characters, so u₂ = 'BCA'. The third substring has 2 different characters, so u₃='DE'.
• Note that a subsequence maintains the original order of characters encountered. The order of characters in each subsequence shown is important.

Function Description:

• Complete the merge_the_tools function in the editor below.
• merge_the_tools has the following parameters:
• string s: the string to analyze
• int k: the size of substrings to analyze
• Prints:  Print each subsequence on a new line. There will be n/k of them. No return value is expected.

Input Format:

• The first line contains a single string, s.
• The second line contains an integer, k, the length of each substring.

Constraints:

• 1 <= n <= 10⁴, where n is the length of s
• 1 <= k <= n
• It is guaranteed that n is a multiple of k.

Sample Input:

STDIN       Function
-----       --------
AABCAAADA   s = 'AABCAAADA'
3           k = 3

Sample Output:

AB
CA
AD

Explanation:

• Split s into n/k = 9/3 = 3 equal parts of length k = 3. Convert each t_i to u_i by removing any subsequent occurrences of non-distinct characters in t_i:

1. t₀ = "AAB" ➡ u₀ = "AB"
2. t₁ = "CAA" ➡ u₁ = "CA"
3. t₂ = "ADA" ➡ u₂ = "AD"

• Print each u_i on a new line.

Solution:

def merge_the_tools(string, k):
    
    for i in range(0,len(string),k):
        uniq_str = ''
        for j in string[i:i+k]:
            if j not in uniq_str:
                uniq_str += j
        print(uniq_str)
        
if __name__ == '__main__':
    string, k = input(), int(input())
    merge_the_tools(string, k)

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