2016. Maximum Difference Between Increasing Elements

#### QUESTION:

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
``````

#### SOLUTION:

``````class Solution {
func maximumDifference(_ nums: [Int]) -> Int {
var result = -1
for indexI in 0..<nums.count-1 {
for indexJ in indexI+1..<nums.count {
if (nums[indexI] < nums[indexJ]) {
result = max(result, nums[indexJ]-nums[indexI])
}
}
}
return result
}
}
``````