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.

maximumDifference.js

/**
 * @param {number[]} nums
 * @return {number}
 */
var maximumDifference = function(nums) {
    // Edge case: If the array has fewer than 2 elements, there's no valid pair.
    if (nums.length < 2) return -1;

    let minSoFar = nums[0]; // Track the smallest element seen so far
    let maxDiff = -1; // Initialize max difference to -1 (default if no valid pair is found)

    // Iterate through the array from index 1 onward
    for (let j = 1; j < nums.length; j++) {
        // If nums[j] is greater than the smallest value encountered, update maxDiff
        if (nums[j] > minSoFar) {
            maxDiff = Math.max(maxDiff, nums[j] - minSoFar);
        }

        // Update minSoFar to track the smallest element
        minSoFar = Math.min(minSoFar, nums[j]);
    }

    return maxDiff; // Return the maximum difference found
};