Package g0801_0900.s0891_sum_of_subsequence_widths

Class Solution

java.lang.Object
g0801_0900.s0891_sum_of_subsequence_widths.Solution
public class Solution extends Object
891 - Sum of Subsequence Widths.

Hard

The width of a sequence is the difference between the maximum and minimum elements in the sequence.

Given an array of integers nums, return the sum of the widths of all the non-empty subsequences of nums. Since the answer may be very large, return it modulo 109 + 7.

A subsequence is a sequence that can be derived from an array by deleting some or no elements without changing the order of the remaining elements. For example, [3,6,2,7] is a subsequence of the array [0,3,1,6,2,2,7].

Example 1:

Input: nums = [2,1,3]

Output: 6

Explanation:

The 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.

Example 2:

Input: nums = [2]

Output: 0

Constraints:

  • 1 <= nums.length <= 105
  • 1 <= nums[i] <= 105

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • sumSubseqWidths

      public int sumSubseqWidths(int[] nums)