Given a string str of size N and an integer K, the task is to generate a string whose substrings of size K can be concatenated to form the given string.
Examples:
Input: str = “abbaaa” K = 2
Output: abaa
Explanation:
All substring of size 2 of parent string “abaa” are “ab”, “ba” and “aa”. After concatenating all these substrings, the given string “abbaaa” can be obtained.
Input: str = “abcbcscsesesesd” K = 3
Output: abcsesd
Explanation :
All substring of size 3 of parent string “abcsesd” are “abc”, “bcs”, “cse”, “ses” and “esd”. After concatenating all these substrings, the given string “abcbcscsesesesd” can be obtained.
Approach:
Follow the steps below to solve the problem:
- We can clearly observe that by concatenating substrings of length K, except the first character, the remaining K-1 characters of any substring is present in the next substring as well.
- Hence, traverse the string and append the first character of every substring to ans and then ignore next the K-1 characters.
- Repeat this process for all substrings except the last substring.
- Append all characters of the last substring to ans.
- Return ans as the required decoded string.
Below is the implementation of the above approach :
C++
// C++ program to generate a // string whose substrings of// length K concatenates to // form given strings#include <bits/stdc++.h> using namespace std;// Function to return the required // required string void decode_String(string str, int K){ string ans = ""; // Iterate the given string for (int i = 0; i < str.size(); i += K) // Append the first // character of every // substring of length K ans += str[i]; // Consider all characters // from the last substring for(int i = str.size() - (K - 1); i < str.size(); i++) ans += str[i]; cout << ans << endl;}// Driver Programint main(){ int K = 3; string str = "abcbcscsesesesd"; decode_String(str, K);} |
Java
// Java program to generate a // string whose substrings of // length K concatenates to // form given strings class GFG{ // Function to return the required // required string public static void decode_String(String str, int K) { String ans = ""; // Iterate the given string for(int i = 0; i < str.length(); i += K) // Append the first // character of every // substring of length K ans += str.charAt(i); // Consider all characters // from the last substring for(int i = str.length() - (K - 1); i < str.length(); i++) ans += str.charAt(i); System.out.println(ans);} // Driver codepublic static void main(String[] args){ int K = 3; String str = "abcbcscsesesesd"; decode_String(str, K); }}// This code is contributed by divyeshrabadiya07 |
Python3
# Python3 program to generate a # string whose substrings of# length K concatenates to # form given strings# Function to return the required # required string def decode_String(st, K): ans = "" # Iterate the given string for i in range(0, len(st), K): # Append the first # character of every # substring of length K ans += st[i] # Consider all characters # from the last substring for i in range(len(st) - (K - 1), len(st)): ans += st[i] print(ans)# Driver codeif __name__ == "__main__": K = 3 st = "abcbcscsesesesd" decode_String(st, K)# This code is contributed by chitranayal |
C#
// C# program to generate a string// whose substrings of length K// concatenates to form given strings using System;class GFG{ // Function to return the required // required string public static void decode_String(String str, int K) { String ans = ""; // Iterate the given string for(int i = 0; i < str.Length; i += K) // Append the first // character of every // substring of length K ans += str[i]; // Consider all characters // from the last substring for(int i = str.Length - (K - 1); i < str.Length; i++) ans += str[i]; Console.WriteLine(ans);} // Driver codepublic static void Main(String[] args){ int K = 3; String str = "abcbcscsesesesd"; decode_String(str, K); }}// This code is contributed by Rohit_ranjan |
Javascript
<script>// JavaScript program to implement// the above approach// Function to return the required // required string function decode_String(str, K) { let ans = ""; // Iterate the given string for(let i = 0; i < str.length; i += K) // Append the first // character of every // substring of length K ans += str[i]; // Consider all characters // from the last substring for(let i = str.length - (K - 1); i < str.length; i++) ans += str[i]; document.write(ans);} // Driver code let K = 3; let str = "abcbcscsesesesd"; decode_String(str, K); // This code is contributed by sanjoy_62.</script> |
Output:
abcsesd
Time Complexity: O(N)
Auxiliary Space: O(N)
Feeling lost in the world of random DSA topics, wasting time without progress? It’s time for a change! Join our DSA course, where we’ll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 neveropen!
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 neveropen!
