Count Special Subsequences - Practice Coding | SlaveCode
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3404. Count Special Subsequences
Medium
30 Points
Array
Hash Table
Math
Enumeration
You are given an array nums consisting of positive integers.
A special subsequence is defined as a subsequence of length 4, represented by indices (p, q, r, s), where p < q < r < s. This subsequence must satisfy the following conditions:
Return the number of different special subsequences in nums.
Examples
Example 1
Input: nums = [1,2,3,4,3,6,1]
Output: 1
Explanation:
There is one special subsequence in nums .
Example 2
Input: nums = [3,4,3,4,3,4,3,4]
Output: 3
Explanation:
There are three special subsequences in nums .
Constraints
7 <= nums.length <= 1000
1 <= nums[i] <= 1000
3404. Count Special Subsequences
Medium
30 Points
Array
Hash Table
Math
Enumeration
You are given an array nums consisting of positive integers.
A special subsequence is defined as a subsequence of length 4, represented by indices (p, q, r, s), where p < q < r < s. This subsequence must satisfy the following conditions:
Return the number of different special subsequences in nums.
Examples
Example 1
Input: nums = [1,2,3,4,3,6,1]
Output: 1
Explanation:
There is one special subsequence in nums .
Example 2
Input: nums = [3,4,3,4,3,4,3,4]
Output: 3
Explanation:
There are three special subsequences in nums .