maxDiffIncreasingEl.js

/**
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

* @param {number[]} nums
* @return {number}
*/
var maximumDifference = function (nums) {
  let minNum = nums[0];
  let maxDiff = -1;
  for (let i = 1; i < nums.length; i++) {
    if (nums[i] > minNum) {
      maxDiff = Math.max(maxDiff, nums[i] - minNum);
    }
    minNum = Math.min(minNum, nums[i]);
  }
  return maxDiff;
};