Check if an array is sorted and rotated
Given an array of N distinct integers. The task is to write a program to check if this array is sorted and rotated. A sorted array is not considered as sorted and rotated, i.e., there should at least one rotation.
Examples:
Input : arr[] = { 3, 4, 5, 1, 2 }
Output : YES
The above array is sorted and rotated.
Sorted array: {1, 2, 3, 4, 5}.
Rotating this sorted array clockwise
by 3 positions, we get: { 3, 4, 5, 1, 2}
Input: arr[] = {7, 9, 11, 12, 5}
Output: YES
Input: arr[] = {1, 2, 3}
Output: NO
Approach:
- Find the minimum element in the array.
- Now, if the array is sorted and then rotated then all the elements before minimum element will be in increasing order and all elements after the minimum element will also be in increasing order.
- Check if all elements before minimum element are in increasing order.
- Check if all elements before minimum element are in increasing order.
- Check if the last element of the array is smaller than the first.
- If all of the above three condition satisfies then print YES otherwise print NO.
Below is the implementation of the above idea:
C++
// CPP program to check if an array is // sorted and rotated clockwise #include <climits> #include <iostream> using namespace std; // Function to check if an array is // sorted and rotated clockwise void checkIfSortRotated(int arr[], int n) { int minEle = INT_MAX; int maxEle = INT_MIN; int minIndex = -1; // Find the minimum element // and it's index for (int i = 0; i < n; i++) { if (arr[i] < minEle) { minEle = arr[i]; minIndex = i; } } int flag1 = 1; // Check if all elements before minIndex // are in increasing order for (int i = 1; i < minIndex; i++) { if (arr[i] < arr[i - 1]) { flag1 = 0; break; } } int flag2 = 1; // Check if all elements after minIndex // are in increasing order for (int i = minIndex + 1; i < n; i++) { if (arr[i] < arr[i - 1]) { flag2 = 0; break; } } // Check if last element of the array // is smaller than the first element. if (flag1 && flag2 && (arr[n - 1] < arr[0])) cout << "YES"; else cout << "NO"; } // Driver code int main() { int arr[] = { 3, 4, 5, 1, 2 }; int n = sizeof(arr) / sizeof(arr[0]); checkIfSortRotated(arr, n); return 0; } |
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Java
// Java program to check if an // array is sorted and rotated // clockwise import java.io.*; class GFG { // Function to check if an array is // sorted and rotated clockwise static void checkIfSortRotated(int arr[], int n) { int minEle = Integer.MAX_VALUE; int maxEle = Integer.MIN_VALUE; int minIndex = -1; // Find the minimum element // and it's index for (int i = 0; i < n; i++) { if (arr[i] < minEle) { minEle = arr[i]; minIndex = i; } } boolean flag1 = true; // Check if all elements before // minIndex are in increasing order for (int i = 1; i < minIndex; i++) { if (arr[i] < arr[i - 1]) { flag1 = false; break; } } boolean flag2 = true; // Check if all elements after // minIndex are in increasing order for (int i = minIndex + 1; i < n; i++) { if (arr[i] < arr[i - 1]) { flag2 = false; break; } } // Check if last element of the array // is smaller than the first element if (flag1 && flag2 && (arr[n - 1] < arr[0])) System.out.println("YES"); else System.out.print("NO"); } // Driver code public static void main (String[] args) { int arr[] = { 3, 4, 5, 1, 2 }; int n = arr.length; checkIfSortRotated(arr, n); } } // This code is contributed // by inder_verma. |
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Python3
# Python3 program to check if an # array is sorted and rotated clockwise import sys # Function to check if an array is # sorted and rotated clockwise def checkIfSortRotated(arr, n): minEle = sys.maxsize maxEle = -sys.maxsize - 1 minIndex = -1 # Find the minimum element # and it's index for i in range(n): if arr[i]< minEle: minEle = arr[i] minIndex = i flag1 = 1 # Check if all elements before # minIndex are in increasing order for i in range(1, minIndex): if arr[i] < arr[i - 1]: flag1 = 0 break flag2 = 2 # Check if all elements after # minIndex are in increasing order for i in range(minIndex + 1, n) : if arr[i] < arr[i - 1]: flag2 = 0 break # Check if last element of the array # is smaller than the first element if (flag1 and flag2 and arr[n - 1] < arr[0]): print("YES") else: print("NO") # Driver code arr = [3, 4, 5, 1, 2 ] n = len(arr) checkIfSortRotated(arr, n) # This code is contributed # by Shrikant13 |
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C#
// C# program to check if an // array is sorted and rotated // clockwise using System; class GFG { // Function to check if an array is // sorted and rotated clockwise static void checkIfSortRotated(int []arr, int n) { int minEle = int.MaxValue; //int maxEle = int.MinValue; int minIndex = -1; // Find the minimum element // and it's index for (int i = 0; i < n; i++) { if (arr[i] < minEle) { minEle = arr[i]; minIndex = i; } } bool flag1 = true; // Check if all elements before // minIndex are in increasing order for (int i = 1; i < minIndex; i++) { if (arr[i] < arr[i - 1]) { flag1 = false; break; } } bool flag2 = true; // Check if all elements after // minIndex are in increasing order for (int i = minIndex + 1; i < n; i++) { if (arr[i] < arr[i - 1]) { flag2 = false; break; } } // Check if last element of the array // is smaller than the first element if (flag1 && flag2 && (arr[n - 1] < arr[0])) Console.WriteLine("YES"); else Console.WriteLine("NO"); } // Driver code public static void Main () { int []arr = { 3, 4, 5, 1, 2 }; int n = arr.Length; checkIfSortRotated(arr, n); } } // This code is contributed // by inder_verma. |
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PHP
<?php // PHP program to check if an // array is sorted and rotated // clockwise // Function to check if an array // is sorted and rotated clockwise function checkIfSortRotated($arr, $n) { $minEle = PHP_INT_MAX; $maxEle = PHP_INT_MIN; $minIndex = -1; // Find the minimum element // and it's index for ($i = 0; $i <$n; $i++) { if ($arr[$i] < $minEle) { $minEle = $arr[$i]; $minIndex = $i; } } $flag1 = 1; // Check if all elements before // minIndex are in increasing order for ( $i = 1; $i <$minIndex; $i++) { if ($arr[$i] < $arr[$i - 1]) { $flag1 = 0; break; } } $flag2 = 1; // Check if all elements after // minIndex are in increasing order for ($i = $minIndex + 1; $i <$n; $i++) { if ($arr[$i] < $arr[$i - 1]) { $flag2 = 0; break; } } // Check if last element of the array // is smaller than the first element if ($flag1 && $flag2 && ($arr[$n - 1] < $arr[0])) echo( "YES"); else echo( "NO"); } // Driver code $arr = array(3, 4, 5, 1, 2); $n = count($arr); checkIfSortRotated($arr, $n); // This code is contributed // by inder_verma. ?> |
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Output:
YES
Recommended Posts:
- Sort a Rotated Sorted Array
- Given a sorted and rotated array, find if there is a pair with a given sum
- Search an element in a sorted and rotated array
- Find the minimum element in a sorted and rotated array
- Find the Rotation Count in Rotated Sorted array
- Count elements less than or equal to a given value in a sorted rotated array
- Count rotations in sorted and rotated linked list
- Check if a given array is pairwise sorted or not
- Check if array can be sorted with one swap
- Check for Majority Element in a sorted array
- Check if the array can be sorted using swaps between given indices only
- Check if a sorted array can be divided in pairs whose sum is k
- Program to check if an array is sorted or not (Iterative and Recursive)
- Check whether a given array is a k sorted array or not
- Sort a nearly sorted (or K sorted) array
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