New Problem Solution - "Check if Array Is Sorted and Rotated"

README.md

@@ -11,6 +11,7 @@ LeetCode
 |---| ----- | -------- | ---------- |
 |1754|[Largest Merge Of Two Strings](https://leetcode.com/problems/largest-merge-of-two-strings/) | [C++](./algorithms/cpp/largestMergeOfTwoStrings/LargestMergeOfTwoStrings.cpp)|Medium|
 |1753|[Maximum Score From Removing Stones](https://leetcode.com/problems/maximum-score-from-removing-stones/) | [C++](./algorithms/cpp/maximumScoreFromRemovingStones/MaximumScoreFromRemovingStones.cpp)|Medium|
+|1752|[Check if Array Is Sorted and Rotated](https://leetcode.com/problems/check-if-array-is-sorted-and-rotated/) | [C++](./algorithms/cpp/checkIfArrayIsSortedAndRotated/CheckIfArrayIsSortedAndRotated.cpp)|Easy|
 |1605|[Find Valid Matrix Given Row and Column Sums](https://leetcode.com/problems/find-valid-matrix-given-row-and-column-sums/) | [C++](./algorithms/cpp/FindValidMatrixGivenRowAndColumnSums/FindValidMatrixGivenRowAndColumnSums.cpp)|Medium|
 |1573|[Number of Ways to Split a String](https://leetcode.com/problems/number-of-ways-to-split-a-string/) | [C++](./algorithms/cpp/NumberOfWaysToSplitString/NumberOfWaysToSplitString.cpp)|Medium|
 |1556|[Thousand Separator](https://leetcode.com/problems/thousand-separator/) | [C++](./algorithms/cpp/thousandSeparator/ThousandSeparator.cpp)|Easy|

algorithms/cpp/checkIfArrayIsSortedAndRotated/CheckIfArrayIsSortedAndRotated.cpp

@@ -0,0 +1,75 @@
+// Source : https://leetcode.com/problems/check-if-array-is-sorted-and-rotated/
+// Author : Hao Chen
+// Date   : 2021-02-11
+
+/***************************************************************************************************** 
+ *
+ * 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
+ ******************************************************************************************************/
+
+class Solution {
+public:
+    bool check(vector<int>& nums) {
+        int len = nums.size();
+        
+        //deal with the rotated case - the first element is greater than last one
+        bool rotate = (nums[0] >= nums[len-1]);
+        
+        for (int i = 0; i < len-1; i++) {
+            if ( nums[i] <= nums[i+1] ) continue;
+            
+            if (rotate) {
+                rotate = false;
+                continue;
+            }
+            return false;
+            
+        }
+        return true;
+    }
+};