g2201_2300.s2281_sum_of_total_strength_of_wizards

Class Solution

java.lang.Object

g2201_2300.s2281_sum_of_total_strength_of_wizards.Solution

public class Solution
extends Object

2281 - Sum of Total Strength of Wizards.

Hard

As the ruler of a kingdom, you have an army of wizards at your command.

You are given a 0-indexed integer array strength, where strength[i] denotes the strength of the ith wizard. For a contiguous group of wizards (i.e. the wizards’ strengths form a subarray of strength), the total strength is defined as the product of the following two values:

• The strength of the weakest wizard in the group.
• The total of all the individual strengths of the wizards in the group.

Return the sum of the total strengths of all contiguous groups of wizards. Since the answer may be very large, return it modulo 109 + 7.

A subarray is a contiguous non-empty sequence of elements within an array.

Example 1:

Input: strength = [1,3,1,2]

Output: 44

Explanation: The following are all the contiguous groups of wizards:

• [1] from [1 ,3,1,2] has a total strength of min([1]) * sum([1]) = 1 * 1 = 1

• [3] from [1, 3 ,1,2] has a total strength of min([3]) * sum([3]) = 3 * 3 = 9

• [1] from [1,3, 1 ,2] has a total strength of min([1]) * sum([1]) = 1 * 1 = 1

• [2] from [1,3,1, 2 ] has a total strength of min([2]) * sum([2]) = 2 * 2 = 4

• [1,3] from [1,3 ,1,2] has a total strength of min([1,3]) * sum([1,3]) = 1 * 4 = 4

• [3,1] from [1, 3,1 ,2] has a total strength of min([3,1]) * sum([3,1]) = 1 * 4 = 4

• [1,2] from [1,3, 1,2 ] has a total strength of min([1,2]) * sum([1,2]) = 1 * 3 = 3

• [1,3,1] from [1,3,1 ,2] has a total strength of min([1,3,1]) * sum([1,3,1]) = 1 * 5 = 5

• [3,1,2] from [1, 3,1,2 ] has a total strength of min([3,1,2]) * sum([3,1,2]) = 1 * 6 = 6

• [1,3,1,2] from [1,3,1,2 ] has a total strength of min([1,3,1,2]) * sum([1,3,1,2]) = 1 * 7 = 7

The sum of all the total strengths is 1 + 9 + 1 + 4 + 4 + 4 + 3 + 5 + 6 + 7 = 44.

Example 2:

Input: strength = [5,4,6]

Output: 213

Explanation: The following are all the contiguous groups of wizards:

• [5] from [5 ,4,6] has a total strength of min([5]) * sum([5]) = 5 * 5 = 25

• [4] from [5, 4 ,6] has a total strength of min([4]) * sum([4]) = 4 * 4 = 16

• [6] from [5,4, 6 ] has a total strength of min([6]) * sum([6]) = 6 * 6 = 36

• [5,4] from [5,4 ,6] has a total strength of min([5,4]) * sum([5,4]) = 4 * 9 = 36

• [4,6] from [5, 4,6 ] has a total strength of min([4,6]) * sum([4,6]) = 4 * 10 = 40

• [5,4,6] from [5,4,6 ] has a total strength of min([5,4,6]) * sum([5,4,6]) = 4 * 15 = 60

The sum of all the total strengths is 25 + 16 + 36 + 36 + 40 + 60 = 213.

Constraints:

• 1 <= strength.length <= 105
• 1 <= strength[i] <= 109

Constructor Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
int	totalStrength(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

totalStrength

public int totalStrength(int[] nums)