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.
C++
// A simple C++ program to find lexicographically minimum rotation // of a given string #include <iostream> #include <algorithm> using namespace std; // This functionr return lexicographically minimum // rotation of str string minLexRotation(string str) { // Find length of given string int n = str.length(); // Create an array of strings to store all rotations string arr[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.substr(i, n); // Sort all rotations sort(arr, arr+n); // Return the first rotation from the sorted array return arr[0]; } // Driver program to test above function int main() { cout << minLexRotation("GEEKSFORGEEKS") << endl; cout << minLexRotation("GEEKSQUIZ") << endl; cout << minLexRotation("BCABDADAB") << endl; } |
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!
