1752. Check if Array Is Sorted and Rotated

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

Rust Solution

struct Solution;

impl Solution {
    fn check(nums: Vec<i32>) -> bool {
        let n = nums.len();
        let mut count = 0;
        for i in 0..n {
            if nums[i] > nums[(i + 1) % n] {
                count += 1;
            }
        }
        count < 2
    }
}

#[test]
fn test() {
    let nums = vec![3, 4, 5, 1, 2];
    let res = true;
    assert_eq!(Solution::check(nums), res);
    let nums = vec![2, 1, 3, 4];
    let res = false;
    assert_eq!(Solution::check(nums), res);
    let nums = vec![1, 2, 3];
    let res = true;
    assert_eq!(Solution::check(nums), res);
    let nums = vec![1, 1, 1];
    let res = true;
    assert_eq!(Solution::check(nums), res);
    let nums = vec![2, 1];
    let res = true;
    assert_eq!(Solution::check(nums), res);
}

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