Problem
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.
Constraints:
1 <= nums.length <= 100
1 <= nums[i] <= 100
Solution
/**
* @param {number[]} nums
* @return {boolean}
*/
var check = function(nums) {
let hasBreak = false;
for (var i = 0; i < nums.length - 1; i++) {
if (nums[i + 1] < nums[i]) {
if (hasBreak) return false;
if (nums[i + 1] <= nums[0] && nums[nums.length - 1] <= nums[0]) {
hasBreak = true;
continue;
}
return false;
}
}
return true;
};
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(1).