public class Solution
extends Object
1512 - Number of Good Pairs\.
Easy
Given an array of integers `nums`, return _the number of **good pairs**_.
A pair `(i, j)` is called _good_ if `nums[i] == nums[j]` and `i` < `j`.
**Example 1:**
**Input:** nums = [1,2,3,1,1,3]
**Output:** 4
**Explanation:** There are 4 good pairs (0,3), (0,4), (3,4), (2,5) 0-indexed.
**Example 2:**
**Input:** nums = [1,1,1,1]
**Output:** 6
**Explanation:** Each pair in the array are _good_.
**Example 3:**
**Input:** nums = [1,2,3]
**Output:** 0
**Constraints:**
* `1 <= nums.length <= 100`
* `1 <= nums[i] <= 100`