697\. Degree of an Array

Easy

Given a non-empty array of non-negative integers `nums`, the **degree** of this array is defined as the maximum frequency of any one of its elements.

Your task is to find the smallest possible length of a (contiguous) subarray of `nums`, that has the same degree as `nums`.

**Example 1:**

**Input:** nums = [1,2,2,3,1]

**Output:** 2

**Explanation:**

    The input array has a degree of 2 because both elements 1 and 2 appear twice.
    Of the subarrays that have the same degree:
    [1, 2, 2, 3, 1], [1, 2, 2, 3], [2, 2, 3, 1], [1, 2, 2], [2, 2, 3], [2, 2]
    The shortest length is 2. So return 2. 

**Example 2:**

**Input:** nums = [1,2,2,3,1,4,2]

**Output:** 6

**Explanation:**

    The degree is 3 because the element 2 is repeated 3 times.
    So [2,2,3,1,4,2] is the shortest subarray, therefore returning 6. 

**Constraints:**

*   `nums.length` will be between 1 and 50,000.
*   `nums[i]` will be an integer between 0 and 49,999.