• Home
• com.github.javadev
• leetcode-in-java
• 1.38
• source code
• readme.md

×

Project download

Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance.
Project price only 1 $

You can buy this project and download/modify it how often you want.

g3301_3400.s3351_sum_of_good_subsequences.readme.md Maven / Gradle / Ivy

3351\. Sum of Good Subsequences

Hard

You are given an integer array `nums`. A **good** subsequence is defined as a subsequence of `nums` where the absolute difference between any **two** consecutive elements in the subsequence is **exactly** 1.

Return the **sum** of all _possible_ **good subsequences** of `nums`.

Since the answer may be very large, return it **modulo** 109 + 7.

**Note** that a subsequence of size 1 is considered good by definition.

**Example 1:**

**Input:** nums = [1,2,1]

**Output:** 14

**Explanation:**

*   Good subsequences are: `[1]`, `[2]`, `[1]`, `[1,2]`, `[2,1]`, `[1,2,1]`.
*   The sum of elements in these subsequences is 14.

**Example 2:**

**Input:** nums = [3,4,5]

**Output:** 40

**Explanation:**

*   Good subsequences are: `[3]`, `[4]`, `[5]`, `[3,4]`, `[4,5]`, `[3,4,5]`.
*   The sum of elements in these subsequences is 40.

**Constraints:**

*   1 <= nums.length <= 105
*   0 <= nums[i] <= 105