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Java-based LeetCode algorithm problem solutions, regularly updated
2080\. Range Frequency Queries
Medium
Design a data structure to find the **frequency** of a given value in a given subarray.
The **frequency** of a value in a subarray is the number of occurrences of that value in the subarray.
Implement the `RangeFreqQuery` class:
* `RangeFreqQuery(int[] arr)` Constructs an instance of the class with the given **0-indexed** integer array `arr`.
* `int query(int left, int right, int value)` Returns the **frequency** of `value` in the subarray `arr[left...right]`.
A **subarray** is a contiguous sequence of elements within an array. `arr[left...right]` denotes the subarray that contains the elements of `nums` between indices `left` and `right` (**inclusive**).
**Example 1:**
**Input**
["RangeFreqQuery", "query", "query"]
[[[12, 33, 4, 56, 22, 2, 34, 33, 22, 12, 34, 56]], [1, 2, 4], [0, 11, 33]]
**Output:** [null, 1, 2]
**Explanation:**
RangeFreqQuery rangeFreqQuery = new RangeFreqQuery([12, 33, 4, 56, 22, 2, 34, 33, 22, 12, 34, 56]);
rangeFreqQuery.query(1, 2, 4); // return 1. The value 4 occurs 1 time in the subarray [33, 4]
rangeFreqQuery.query(0, 11, 33); // return 2. The value 33 occurs 2 times in the whole array.
**Constraints:**
* 1 <= arr.length <= 105
* 1 <= arr[i], value <= 104
* `0 <= left <= right < arr.length`
* At most 105
calls will be made to `query`