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Java Solution for LeetCode algorithm problems, continually updating

There is a newer version: 1.24

493\. Reverse Pairs

Hard

Given an integer array `nums`, return _the number of **reverse pairs** in the array_.

A reverse pair is a pair `(i, j)` where `0 <= i < j < nums.length` and `nums[i] > 2 * nums[j]`.

**Example 1:**

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

**Output:** 2

**Example 2:**

**Input:** nums = [2,4,3,5,1]

**Output:** 3

**Constraints:**

*   1 <= nums.length <= 5 * 10⁴
*   -2³¹ <= nums[i] <= 2³¹ - 1