# GeetCode Hub

Given a (0-indexed) integer array `nums` and two integers `low` and `high`, return the number of nice pairs.

A nice pair is a pair `(i, j)` where `0 <= i < j < nums.length` and `low <= (nums[i] XOR nums[j]) <= high`.

Example 1:

```Input: nums = [1,4,2,7], low = 2, high = 6
Output: 6
Explanation: All nice pairs (i, j) are as follows:
- (0, 1): nums[0] XOR nums[1] = 5
- (0, 2): nums[0] XOR nums[2] = 3
- (0, 3): nums[0] XOR nums[3] = 6
- (1, 2): nums[1] XOR nums[2] = 6
- (1, 3): nums[1] XOR nums[3] = 3
- (2, 3): nums[2] XOR nums[3] = 5
```

Example 2:

```Input: nums = [9,8,4,2,1], low = 5, high = 14
Output: 8
Explanation: All nice pairs (i, j) are as follows:
​​​​​    - (0, 2): nums[0] XOR nums[2] = 13
- (0, 3): nums[0] XOR nums[3] = 11
- (0, 4): nums[0] XOR nums[4] = 8
- (1, 2): nums[1] XOR nums[2] = 12
- (1, 3): nums[1] XOR nums[3] = 10
- (1, 4): nums[1] XOR nums[4] = 9
- (2, 3): nums[2] XOR nums[3] = 6
- (2, 4): nums[2] XOR nums[4] = 5```

Constraints:

• `1 <= nums.length <= 2 * 104`
• `1 <= nums[i] <= 2 * 104`
• `1 <= low <= high <= 2 * 104`

class Solution { public int countPairs(int[] nums, int low, int high) { } }