Given an array arr[] of size N (consisting of duplicates), the task is to check if the given array can be converted to a non-decreasing array by rotating it. If it’s not possible to do so, then print “No“. Otherwise, print “Yes“.
Examples:
Input: arr[] = {3, 4, 5, 1, 2}
Output: Yes
Explanation: After 2 right rotations, the array arr[] modifies to {1, 2, 3, 4, 5}Input: arr[] = {1, 2, 4, 3}
Output: No
Approach: The idea is based on the fact that a maximum of N distinct arrays can be obtained by rotating the given array and check for each individual rotated array, whether it is non-decreasing or not. Follow the steps below to solve the problem:
- Initialize a vector, say v, and copy all the elements of the original array into it.
- Sort the vector v.
- Traverse the original array and perform the following steps:
- Rotate by 1 in each iteration.
- If the array becomes equal to vector v, print “Yes“. Otherwise, print “No“.
Below is the implementation of the above approach:
Java
// Java program for the above approachimport java.util.*; class GFG{ // Function to check if a // non-decreasing array can be obtained // by rotating the original array static void rotateArray(int[] arr, int N) { // Stores copy of original array int[] v = arr; // Sort the given vector Arrays.sort(v); // Traverse the array for (int i = 1; i <= N; ++i) { // Rotate the array by 1 int x = arr[N - 1]; i = N - 1; while(i > 0){ arr[i] = arr[i - 1]; arr[0] = x; i -= 1; } // If array is sorted if (arr == v) { System.out.print("YES"); return; } } // If it is not possible to // sort the array System.out.print("NO"); } // Driver Code public static void main(String[] args) { // Given array int[] arr = { 3, 4, 5, 1, 2 }; // Size of the array int N = arr.length; // Function call to check if it is possible // to make array non-decreasing by rotating rotateArray(arr, N); }} // This code is contributed by splevel62. |
YES
Time Complexity: O(N2)
Auxiliary Space: O(N)
Please refer complete article on Modify given array to a non-decreasing array by rotation for more details!
