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Lexicographically all Shortest Palindromic Substrings from a given string
• Difficulty Level : Medium
• Last Updated : 18 May, 2020

Given a string s of size N. The task is to find lexicographically all shortest palindromic substrings from the given string.

Examples:

Input: s= “programming”
Output: a g i m n o p r
Explanation:
The Lexicographical shortest palindrome substring for the word “programming” will be the single characters from the given string. Hence, the output is : a g i m n o p r.

Input: s= “geeksforgeeks”
Output: e f g k o r s

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

To solve the problem mentioned above the very first observation is that the shortest palindromic substring will be of size 1. So as per the problem statement, we have to find all distinct substring of size 1 lexicographically which means all the characters in the given string.

Below is the implementation of the above approach:

## C++

 `// C++ program to find Lexicographically all``// Shortest Palindromic Substrings from a given string`` ` `#include ``using` `namespace` `std;`` ` `// Function to find all lexicographically``// shortest palindromic substring``void` `shortestPalindrome(string s)``{`` ` `    ``// Array to keep track of alphabetic characters``    ``int` `abcd = { 0 };`` ` `    ``for` `(``int` `i = 0; i < s.length(); i++)``        ``abcd[s[i] - 97] = 1;`` ` `    ``// Iterate to print all lexicographically shortest substring``    ``for` `(``int` `i = 0; i < 26; i++) {``        ``if` `(abcd[i] == 1)``            ``cout << ``char``(i + 97) << ``" "``;``    ``}``}`` ` `// Driver code``int` `main()``{``    ``string s = ``"geeksforgeeks"``;`` ` `    ``shortestPalindrome(s);`` ` `    ``return` `0;``}`

## Java

 `// Java program to find Lexicographically all``// Shortest Palindromic Substrings from a given string``class` `Main``{``    ``// Function to find all lexicographically``    ``// shortest palindromic substring``    ``static` `void` `shortestPalindrome(String s)``    ``{`` ` `        ``// Array to keep track of ``        ``// alphabetic characters``        ``int``[] abcd = ``new` `int``[``26``];`` ` `        ``for` `(``int` `i = ``0``; i < s.length(); i++)``            ``abcd[s.charAt(i) - ``97``] = ``1``;`` ` `        ``// Iterate to print all lexicographically``        ``// shortest substring``        ``for` `(``int` `i = ``0``; i < ``26``; i++)``        ``{``            ``if` `(abcd[i] == ``1``) ``            ``{``                ``System.out.print((``char``)(i + ``97``) + ``" "``);``            ``}``        ``}``    ``}`` ` `    ``// Driver code``    ``public` `static` `void` `main(String[] args)``    ``{``        ``String s = ``"geeksforgeeks"``;``        ``shortestPalindrome(s);``    ``}``}`

## Python3

 `# C++ program to find Lexicographically all``# Shortest Palindromic Substrings from a given string`` ` `# Function to find all lexicographically ``# shortest palindromic substring``def` `shortestPalindrome (s) :``     ` `    ``# Array to keep track of alphabetic characters``    ``abcd ``=` `[``0``]``*``26`` ` `    ``for` `i ``in` `range``(``len``(s)):``        ``abcd[``ord``(s[i])``-``97``] ``=` `1``     ` `    ``# Iterate to print all lexicographically shortest substring``    ``for` `i ``in` `range``(``26``): ``        ``if` `abcd[i]``=``=` `1` `:``            ``print``( ``chr``(i ``+` `97``), end ``=``' '` `)`` ` `# Driver code``s ``=` `"geeksforgeeks"`` ` `shortestPalindrome (s)`

## C#

 `// C# program to find Lexicographically ``// all shortest palindromic substrings``// from a given string``using` `System;`` ` `class` `GFG{``     ` `// Function to find all lexicographically ``// shortest palindromic substring ``static` `void` `shortestPalindrome(``string` `s) ``{ `` ` `    ``// Array to keep track of``    ``// alphabetic characters ``    ``int``[] abcd = ``new` `int``; `` ` `    ``for``(``int` `i = 0; i < s.Length; i++) ``       ``abcd[s[i] - 97] = 1; `` ` `    ``// Iterate to print all lexicographically ``    ``// shortest substring ``    ``for``(``int` `i = 0; i < 26; i++)``    ``{ ``       ``if` `(abcd[i] == 1)``       ``{ ``           ``Console.Write((``char``)(i + 97) + ``" "``); ``       ``} ``    ``} ``} `` ` `// Driver code ``static` `public` `void` `Main(``string``[] args) ``{ ``    ``string` `s = ``"geeksforgeeks"``; ``    ``shortestPalindrome(s); ``} ``} `` ` `// This code is contributed by AnkitRai01`
Output:
```e f g k o r s
```

Time Complexity: O(N), where N is the size of the string.

Space Complexity: O(1)

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