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4088. Difference Between Peaks and Valleys

DifficultyEasy

Description

You are given an integer array nums of length n.

An index i is called a peak if all of the following conditions hold:

  • 0 < i < n - 1
  • nums[i] > nums[i - 1]
  • nums[i] > nums[i + 1]

An index i is called a valley if all of the following conditions hold:

  • 0 < i < n - 1
  • nums[i] < nums[i - 1]
  • nums[i] < nums[i + 1]

Return an integer denoting the difference between the sum of all peak values and the sum of all valley values.

 

Example 1:

Input: nums = [1,5,2,4,1,3,0]

Output: 9

Explanation:

  • The peak values are nums[1] = 5, nums[3] = 4, and nums[5] = 3.
  • The valley values are nums[2] = 2 and nums[4] = 1.
  • The difference between the sum of the peak values and the sum of the valley values is (5 + 4 + 3) - (2 + 1) = 9. Hence, the answer is 9.

Example 2:

Input: nums = [-5,-6,-1,-2,5,3,2]

Output: 12

Explanation:

  • The peak values are nums[2] = -1 and nums[4] = 5.
  • The valley values are nums[1] = -6 and nums[3] = -2.
  • The difference between the sum of the peak values and the sum of the valley values is (-1 + 5) - (-6 + (-2)) = 12. Hence, the answer is 12.

Example 3:

Input: nums = [6,5,2,5,5,3,6]

Output: -5

Explanation:

  • There are no peak values in the array.
  • The valley values are nums[2] = 2 and nums[5] = 3.
  • The difference between the sum of the peak values and the sum of the valley values is (0) - (2 + 3) = -5. Hence, the answer is -5.

 

Constraints:

  • 3 <= n == nums.length <= 100
  • -100 <= nums[i] <= 100

Solutions

Solution 1

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