/**
 * HashMap and Stack
 * Time O(N + M) | Space O(N)
 * https://leetcode.com/problems/next-greater-element-i
 * @param {number[]} nums1
 * @param {number[]} nums2
 * @return {number[]}
 */

var nextGreaterElement = function (nums1, nums2) {
    const subsetMap = new Map(nums1.map((val, i) => [val, i]));
    const res = new Array(nums1.length).fill(-1);

    let stack = [];

    for (let num of nums2) {
        while (stack.length && num > stack.at(-1)) {
            const val = stack.pop();
            const idx = subsetMap.get(val);
            res[idx] = num;
        }

        if (subsetMap.has(num)) stack.push(num);
    }

    return res;
};