Solving Sum of Subsequence Widths in go. Please try yourself first to solve the problem and submit your implementation to LeetCode before looking into solution.

Problem Description

Given an array of integers A, consider all non-empty subsequences of A.

For any sequence S, let the width of S be the difference between the maximum and minimum element of S.

Return the sum of the widths of all subsequences of A.

As the answer may be very large, return the answer modulo 10^9 + 7.

Example 1:

Input: [2,1,3]
Output: 6
Explanation:
Subsequences are [1], [2], [3], [2,1], [2,3], [1,3], [2,1,3].
The corresponding widths are 0, 0, 0, 1, 1, 2, 2.
The sum of these widths is 6.

Note:

  • 1 <= A.length <= 20000
  • 1 <= A[i] <= 20000
    [2,1,3]:[1],[2],[3],[2,1],[2,3],[1,3],[2,1,3]
    [1,2,3]:[1],[2],[3],[1,2],[2,3],[1,3],[1,2,3]

See the full details of the problem Sum of Subsequence Widths at LeetCode

Originally posted at: @github.com/halfrost/LeetCode-Go