Check if Array Is Sorted and Rotated - Array - Easy - LeetCode
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Check if Array Is Sorted and Rotated - Array - Easy - LeetCode

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  • 1An array is considered sorted and rotated if it was originally sorted in non-decreasing order and then rotated some positions.
  • 2The algorithm checks for a single point where the order breaks to determine if the array can be a rotated version of a sorted array.
  • 3Examples demonstrate that arrays with duplicates or no rotation can still satisfy the sorted and rotated condition.

AI-generated summary · May not capture all nuances

Key Insight
AskGif

"An array is considered sorted and rotated if it was originally sorted in non-decreasing order and then rotated some positions."

Check if Array Is Sorted and Rotated - Array - Easy - LeetCode

Given an array nums, return true if the array was originally sorted in non-decreasing order, then rotated some number of positions (including zero). Otherwise, return false.

There may be duplicates in the original array.

Note: An array A rotated by x positions results in an array B of the same length such that A[i] == B[(i+x) % A.length], where % is the modulo operation.

Example 1:

Input: nums = [3,4,5,1,2] Output: true Explanation: [1,2,3,4,5] is the original sorted array. You can rotate the array by x = 3 positions to begin on the the element of value 3: [3,4,5,1,2]. Example 2:

Input: nums = [2,1,3,4] Output: false Explanation: There is no sorted array once rotated that can make nums. Example 3:

Input: nums = [1,2,3] Output: true Explanation: [1,2,3] is the original sorted array. You can rotate the array by x = 0 positions (i.e. no rotation) to make nums. Example 4:

Input: nums = [1,1,1] Output: true Explanation: [1,1,1] is the original sorted array. You can rotate any number of positions to make nums. Example 5:

Input: nums = [2,1] Output: true Explanation: [1,2] is the original sorted array. You can rotate the array by x = 5 positions to begin on the element of value 2: [2,1].

Constraints:

1 <= nums.length <= 100 1 <= nums[i] <= 100

public class Solution {
 public bool Check(int[] nums) {
 bool isRotationFound = false;
 bool isSorted = true;
 for(int i=1;i<nums.Length;i++){
 if(nums[i-1]>nums[i]){
 if(isRotationFound){
 return false;
 }
 else{
 isRotationFound = true;
 }
 }
 }
 
 if(isRotationFound){
 if(nums[nums.Length-1] > nums[0]){
 return false;
 }
 }
 
 return true;
 }
}

Time Complexity: O(n) Space Complexity: O(1)

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sumitc91

Published on 31 March 2021 · 1 min read · 269 words

Part of AskGif Blog · coding

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Check if Array Is Sorted and Rotated - Array - Easy - LeetCode | AskGif Blog