2016. Maximum Difference Between Increasing Elements

https://leetcode.com/problems/maximum-difference-between-increasing-elements

Description

Given a 0-indexed integer array nums of size n, find the maximum difference between nums[i] and nums[j] (i.e., nums[j] - nums[i]), such that 0 <= i < j < n and nums[i] < nums[j].

Return the maximum difference. If no such i and j exists, return -1.

Example 1:

**Input:** nums = [7,**1**,**5**,4]
**Output:** 4
**Explanation:**
The maximum difference occurs with i = 1 and j = 2, nums[j] - nums[i] = 5 - 1 = 4.
Note that with i = 1 and j = 0, the difference nums[j] - nums[i] = 7 - 1 = 6, but i > j, so it is not valid.

Example 2:

**Input:** nums = [9,4,3,2]
**Output:** -1
**Explanation:**
There is no i and j such that i < j and nums[i] < nums[j].

Example 3:

**Input:** nums = [**1**,5,2,**10**]
**Output:** 9
**Explanation:**
The maximum difference occurs with i = 0 and j = 3, nums[j] - nums[i] = 10 - 1 = 9.

Constraints:

• n == nums.length

• 2 <= n <= 1000

• 1 <= nums[i] <= 109

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