Watch 10 video solutions for Arithmetic Slices II - Subsequence, a hard level problem involving Array, Dynamic Programming. This walkthrough by NeetCodeIO has 17,990 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
Given an integer array nums, return the number of all the arithmetic subsequences of nums.
A sequence of numbers is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the same.
[1, 3, 5, 7, 9], [7, 7, 7, 7], and [3, -1, -5, -9] are arithmetic sequences.[1, 1, 2, 5, 7] is not an arithmetic sequence.A subsequence of an array is a sequence that can be formed by removing some elements (possibly none) of the array.
[2,5,10] is a subsequence of [1,2,1,2,4,1,5,10].The test cases are generated so that the answer fits in 32-bit integer.
Example 1:
Input: nums = [2,4,6,8,10] Output: 7 Explanation: All arithmetic subsequence slices are: [2,4,6] [4,6,8] [6,8,10] [2,4,6,8] [4,6,8,10] [2,4,6,8,10] [2,6,10]
Example 2:
Input: nums = [7,7,7,7,7] Output: 16 Explanation: Any subsequence of this array is arithmetic.
Constraints:
1 <= nums.length <= 1000-231 <= nums[i] <= 231 - 1