public class Solution
extends Object
2179 - Count Good Triplets in an Array\.
Hard
You are given two **0-indexed** arrays `nums1` and `nums2` of length `n`, both of which are **permutations** of `[0, 1, ..., n - 1]`.
A **good triplet** is a set of `3` **distinct** values which are present in **increasing order** by position both in `nums1` and `nums2`. In other words, if we consider pos1v as the index of the value `v` in `nums1` and pos2v as the index of the value `v` in `nums2`, then a good triplet will be a set `(x, y, z)` where `0 <= x, y, z <= n - 1`, such that pos1x < pos1y < pos1z and pos2x < pos2y < pos2z.
Return _the **total number** of good triplets_.
**Example 1:**
**Input:** nums1 = [2,0,1,3], nums2 = [0,1,2,3]
**Output:** 1
**Explanation:**
There are 4 triplets (x,y,z) such that pos1x < pos1y < pos1z. They are (2,0,1), (2,0,3), (2,1,3), and (0,1,3).
Out of those triplets, only the triplet (0,1,3) satisfies pos2x < pos2y < pos2z.
Hence, there is only 1 good triplet.
**Example 2:**
**Input:** nums1 = [4,0,1,3,2], nums2 = [4,1,0,2,3]
**Output:** 4
**Explanation:** The 4 good triplets are (4,0,3), (4,0,2), (4,1,3), and (4,1,2).
**Constraints:**
* `n == nums1.length == nums2.length`
* 3 <= n <= 105
* `0 <= nums1[i], nums2[i] <= n - 1`
* `nums1` and `nums2` are permutations of `[0, 1, ..., n - 1]`.