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.

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. 

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

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. 

• n == nums.length
• 2 <= n <= 1000
• 1 <= nums[i] <= 109

implSolution{pubfnmaximum_difference(nums:Vec<i32>) -> i32{letmut min = nums[0];letmut max = nums[0];letmut ret = -1;for&num in&nums[1..]{if num < min { min = num; max = num;}elseif num > max { max = num; ret = ret.max(max - min);}} ret }}