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 Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
int	sumSubseqWidths(int[] nums)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Solution

public Solution()

Method Detail

sumSubseqWidths

public int sumSubseqWidths(int[] nums)