Given a non-empty array, find the smallest length of a contiguous subarray that has the same degree as the array.
Example 1:
Input: nums = [1, 2, 2, 3, 1]
Output: 2
Explanation: The degree is 2 (elements 1 and 2 both appear twice).
The shortest subarray with degree 2 is [2, 2] with length 2.
Example 2:
Input: nums = [1, 2, 2, 3, 1, 4, 2]
Output: 6
Explanation: The degree is 3 (element 2 appears 3 times).
The shortest subarray with degree 3 is [2, 2, 3, 1, 4, 2] with length 6.