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: GEEKSQUIZ Output: EEKSQUIZG Input: GFG Output: FGG Input: GEEKSFORGEEKS Output: EEKSFORGEEKSG
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.
Javascript
<script> // A simple Javascript program to find // lexicographically minimum rotation // of a given String // This functionr return lexicographically // minimum rotation of str function minLexRotation(str) { // Find length of given String let n = str.length; // Create an array of strings // to store all rotations let arr = new Array(n); // Create a concatenation of // String with itself let concat = str + str; // One by one store all rotations // of str in array. A rotation is // obtained by getting a substring of concat for(let i = 0; i < n; i++) { arr[i] = concat.substring(i, i + n); } // Sort all rotations arr.sort(); // Return the first rotation // from the sorted array return arr[0]; } // Driver code document.write(minLexRotation("GEEKSFORGEEKS") + "</br>"); document.write(minLexRotation("GEEKSQUIZ") + "</br>"); document.write(minLexRotation("BCABDADAB") + "</br>"); // This code is contributed by divyeshrabadiya07 </script> |
Output:
EEKSFORGEEKSG 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!
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