Given a string, we need to find the minimum number of rotations required to get the same string. Examples:
Input : s = “geeks”
Output : 5Input : s = “aaaa”
Output : 1
The idea is based on below post. A Program to check if strings are rotations of each other or not Step 1 : Initialize result = 0 (Here result is count of rotations) Step 2 : Take a temporary string equals to original string concatenated with itself. Step 3 : Now take the substring of temporary string of size same as original string starting from second character (or index 1). Step 4 : Increase the count. Step 5 : Check whether the substring becomes equal to original string. If yes, then break the loop. Else go to step 2 and repeat it from the next index.
Java
// Java program to determine minimum number// of rotations required to yield same// string.import java.util.*;class GFG{ // Returns count of rotations to get the // same string back. static int findRotations(String str) { // tmp is the concatenated string. String tmp = str + str; int n = str.length(); for (int i = 1; i <= n; i++) { // substring from i index of original // string size. String substring = tmp.substring( i, i+str.length()); // if substring matches with original string // then we will come out of the loop. if (str.equals(substring)) return i; } return n; } // Driver Method public static void main(String[] args) { String str = "aaaa"; System.out.println(findRotations(str)); }}/* This code is contributed by Mr. Somesh Awasthi */ |
Output:
3
Time Complexity: O(n2) Please refer complete article on Minimum rotations required to get the same string for more details!
Auxiliary Space: O(n), The extra space is used to store the copied string in tmp variable.
