Longest Subarray with Balanced Frequencies

# Longest Subarray with Balanced Frequencies You are given an integer array `nums`. A nonempty contiguous subarray is frequency balanced when either: - It contains just one distinct value, with any positive number of occurrences; or - There is a positive integer `f` such that each distinct value occurs either `f` or `2 * f` times, and at least one value has each frequency. Return the length of the longest frequency-balanced subarray. ### Function `int getLength(vector<int>& nums)` ### Example 1 **Input:** `nums = [8, 8, 3, 8, 3, 8]` **Output:** `6` **Explanation:** In the whole array, `8` occurs four times and `3` occurs twice. These are the required two frequencies for `f = 2`. ### Example 2 **Input:** `nums = [4, 4, 9, 9]` **Output:** `3` **Explanation:** The whole array has two distinct values that each occur twice, so it is not balanced: both required frequencies must occur. The subarray `[4, 4, 9]` has frequencies `2` and `1` and is balanced, giving length `3`. ### Constraints - `1 <= nums.length <= 1000` - `1 <= nums[i] <= 1000000000` ### Clarifications - A subarray consists of consecutive elements; it is not an arbitrary subsequence. - A subarray with multiple distinct values all occurring equally often does not qualify. - Only values present in the chosen subarray participate in the frequency condition. - A singleton always qualifies, so the answer is at least `1`. ### What a Strong Answer Covers - Applying the one-distinct-value exception separately from the two-frequency rule. - Requiring exactly the allowed frequency levels, with both present. - Finding the longest qualifying contiguous range while supporting large element values.