Given a palindromic string str containing only lowercase letters, the task is to print the lexicographically smallest string, by replacing exactly one character, such the string is not a palindrome.
Examples:
Input: str = “abccba”
Output: “aaccba”
Explanation:
Lexicographically smallest non-palindromic string possible is “aaccba”, here we have replaced the second letter ‘b’ by an ‘a’ which makes it a non palindrome.Input: str = “a”
Output: -1
Explanation:
A single character is always a palindrome hence we cannot replace the value. Therefore the output is -1.
Approach: To solve the problem mentioned above we will check only half of the string and replace all characters which are not ‘a’ to the character ‘a’ itself. The edge case for the question is if there is only one character, we will return an empty string. Otherwise, if all the characters are the same then we will replace the last character only with character ‘b’.
Below is the implementation of the above approach:
C++
// C++ program to make the string// lexicographically smallest non// palindromic string by replacing// exactly one character#include <bits/stdc++.h>using namespace std;// Function to find the required stringstring findStr(string S){ // length of the string int n = S.size(); // Iterate till half of the string for (int i = 0; i < n / 2; ++i) { // replacing a non 'a' char with 'a' if (S[i] != 'a') { S[i] = 'a'; return S; } } // Check if there is no 'a' in string // we replace last char of string by 'b' S[n - 1] = 'b'; // If the input is a single character return n < 2 ? " -1 " : S;}// Driver codeint main(){ string str = "a"; cout << findStr(str) << endl; string str1 = "abccba"; cout << findStr(str1) << endl; return 0;} |
Java
// Java program to make the string// lexicographically smallest non// palindromic string by replacing// exactly one characterimport java.util.*;class GFG {// Function to find the required stringstatic String findStr(String S){ StringBuilder sb = new StringBuilder(S); // length of the string int n = sb.length(); // Iterate till half of the string for (int i = 0; i < n / 2; ++i) { // replacing a non 'a' char with 'a' if (sb.charAt(i) != 'a') { sb.setCharAt(i, 'a'); return sb.toString(); } } // Check if there is no 'a' in string // we replace last char of string by 'b' sb.setCharAt(n - 1, 'b'); // If the input is a single character return n < 2 ? " -1 " : sb.toString();}// Driver codepublic static void main(String[] args){ String str = "a"; System.out.println(findStr(str)); String str1 = "abccba"; System.out.println(findStr(str1));}}// This code is contributed by offbeat |
Python3
# Python3 program to make the string # lexicographically smallest non # palindromic string by replacing # exactly one character # Function to find the required string def findStr(S): S = list(S) # Length of the string n = len(S) # Iterate till half of the string for i in range(0, n // 2): # Replacing a non 'a' char with 'a' if S[i] != 'a': S[i] = 'a' return (''.join(S)) # Check if there is no 'a' in string # we replace last char of string by 'b' S[n - 1] = 'b' # If the input is a single character if n < 2: return '-1' else: return (''.join(S)) # Driver Code if __name__=='__main__': str1 = 'a' print(findStr(str1)) str2 = 'abccba' print(findStr(str2))# This code is contributed by rutvik_56 |
C#
// C# program to make the string// lexicographically smallest non// palindromic string by replacing// exactly one characterusing System;class GFG{// Function to find the required stringstatic String findStr(char []S){ // Length of the string int n = S.Length; // Iterate till half of the string for(int i = 0; i < n / 2; ++i) { // Replacing a non 'a' char with 'a' if (S[i] != 'a') { S[i] = 'a'; return new String(S); } } // Check if there is no 'a' in string // we replace last char of string by 'b' S[n - 1] = 'b'; // If the input is a single character return n < 2 ? " -1 " : new String(S);}// Driver codepublic static void Main(String[] args){ String str = "a"; Console.WriteLine(findStr(str.ToCharArray())); String str1 = "abccba"; Console.WriteLine(findStr(str1.ToCharArray()));}}// This code is contributed by 29AjayKumar |
Javascript
<script>// Javascript program to make the string// lexicographically smallest non// palindromic string by replacing// exactly one character// Function to find the required stringfunction findStr(S){ // length of the string var n = S.length; // Iterate till half of the string for (var i = 0; i < n / 2; ++i) { // replacing a non 'a' char with 'a' if (S[i] != 'a') { S[i] = 'a'; return S.join("");; } } // Check if there is no 'a' in string // we replace last char of string by 'b' S[n - 1] = 'b'; // If the input is a single character return n < 2 ? " -1 " : S.join("");;}// Driver codevar str = "a";document.write( findStr(Array.from(str)) + "<br>");var str1 = "abccba";document.write( findStr(Array.from(str1)));</script> |
Output:
-1 aaccba
Time Complexity: O(N)
Auxiliary Space: O(1)
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!
