Java Program to Find Lexicographically minimum string rotation | Set 1
Write code to find lexicographic minimum in a circular array, e.g. for the array BCABDADAB, the lexicographic minimum is ABBCABDAD.
Source: Google Written Test
More Examples:
Input: BeginnerQUIZ Output: EEKSQUIZG Input: GFG Output: FGG Input: w3wiki Output: EEKSFORBeginnerG
Following is a simple solution. Let the given string be ‘str’
1) Concatenate ‘str’ with itself and store in a temporary string say ‘concat’.
2) Create an array of strings to store all rotations of ‘str’. Let the array be ‘arr’.
3) Find all rotations of ‘str’ by taking substrings of ‘concat’ at index 0, 1, 2..n-1. Store these rotations in arr[]
4) Sort arr[] and return arr[0].
Following is the implementation of above solution.
Java
// A simple Java program to find // lexicographically minimum rotation // of a given String import java.util.*; class GFG { // This functionr return lexicographically // minimum rotation of str static String minLexRotation(String str) { // Find length of given String int n = str.length(); // Create an array of strings // to store all rotations String arr[] = new String[n]; // Create a concatenation of // String with itself String concat = str + str; // One by one store all rotations // of str in array. A rotation is // obtained by getting a substring of concat for (int i = 0; i < n; i++) { arr[i] = concat.substring(i, i + n); } // Sort all rotations Arrays.sort(arr); // Return the first rotation // from the sorted array return arr[0]; } // Driver code public static void main(String[] args) { System.out.println(minLexRotation("w3wiki")); System.out.println(minLexRotation("BeginnerQUIZ")); System.out.println(minLexRotation("BCABDADAB")); } } // This code is contributed by 29AjayKumar |
Output:
EEKSFORBeginnerG EEKSQUIZG ABBCABDAD
Time complexity of the above solution is O(n2Logn) under the assumption that we have used a O(nLogn) sorting algorithm.
Please refer complete article on Lexicographically minimum string rotation | Set 1 for more details!