Given a string str containing lowercase alphabets (a – z). The task is to print the string after rearranging some characters such that the string becomes non-palindromic. If its impossible to make the string non-palindrome then print -1.
Examples:
Input: str = “abba”
Output: aabbInput: str = “zzz”
Output: -1
Approach: If all the characters in the string are same then no matter how you rearrange the characters, string will remain the same and will be palindromic. Now, if a non-palindromic arrangement exists, the best way to rearrange the characters is to sort the string which will form continuous segment of same characters and will never be palindromic. In order to reduce the time required to sort the string, we can store the frequencies of all the 26 characters and print them in sorted manner.
Below is the implementation of the above approach:
C++
// CPP Program to rearrange letters of string // to find a non-palindromic string if it exists #include <bits/stdc++.h> using namespace std; // Function to print the non-palindromic string // if it exists, otherwise prints -1 void findNonPalinString(string s) { int freq[26] = { 0 }, flag = 0; for (int i = 0; i < s.size(); i++) { // If all characters are not // same, set flag to 1 if (s[i] != s[0]) flag = 1; // Update frequency of the current character freq[s[i] - 'a']++; } // If all characters are same if (!flag) cout << "-1"; else { // Print characters in sorted manner for (int i = 0; i < 26; i++) for (int j = 0; j < freq[i]; j++) cout << char('a' + i); } } // Driver Code int main() { string s = "abba"; findNonPalinString(s); return 0; } |
Java
// Java Program to rearrange letters of string // to find a non-palindromic string if it exists class GfG { // Function to print the non-palindromic string // if it exists, otherwise prints -1 static void findNonPalinString(char s[]) { int freq[] = new int[26]; int flag = 0; for (int i = 0; i < s.length; i++) { // If all characters are not // same, set flag to 1 if (s[i] != s[0]) flag = 1; // Update frequency of // the current character freq[s[i] - 'a']++; } // If all characters are same if (flag == 0) System.out.println("-1"); else { // Print characters in sorted manner for (int i = 0; i < 26; i++) for (int j = 0; j < freq[i]; j++) System.out.print((char)('a' + i)); } } // Driver Code public static void main(String[] args) { String s = "abba"; findNonPalinString(s.toCharArray()); } } // This code is contributed by // Prerna Saini. |
Python3
# Python3 Program to rearrange letters of string # to find a non-palindromic string if it exists # Function to print the non-palindromic string # if it exists, otherwise prints -1 def findNonPalinString(s): freq = [0] * (26) flag = 0 for i in range(0, len(s)): # If all characters are not same, # set flag to 1 if s[i] != s[0]: flag = 1 # Update frequency of the current # character freq[ord(s[i]) - ord('a')] += 1 # If all characters are same if not flag: print("-1") else: # Print characters in sorted manner for i in range(0, 26): for j in range(0, freq[i]): print(chr(ord('a') + i), end = "") # Driver Code if __name__ == "__main__": s = "abba" findNonPalinString(s) # This code is contributed by # Rituraj Jain |
C#
// C# Program to rearrange letters // of string to find a non-palindromic // string if it exists using System; class GfG { // Function to print the // non-palindromic string // if it exists, otherwise // prints -1 static void findNonPalinString(char []s) { int []freq = new int[26]; int flag = 0; for (int i = 0; i < s.Length; i++) { // If all characters are not // same, set flag to 1 if (s[i] != s[0]) flag = 1; // Update frequency of // the current character freq[s[i] - 'a']++; } // If all characters are same if (flag == 0) Console.WriteLine("-1"); else { // Print characters in sorted manner for (int i = 0; i < 26; i++) for (int j = 0; j < freq[i]; j++) Console.Write((char)('a' + i)); } } // Driver Code public static void Main() { string s = "abba"; findNonPalinString(s.ToCharArray()); } } // This code is contributed by Ryuga |
aabb
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