题目前置题目：https://leetcode.cn/problems/number-of-good-pairs/description/当前题目：https://leetcode.cn/problems/count-special-subsequences/description/题解将\(nums[p]*nums[r]=nums[r]*nums[s]\)变形为\(\frac{nums[p]}{nums[q]}=\frac{nums[s]}{nums[r