496. 下一个更大元素 I

class Solution {
    public int[] nextGreaterElement(int[] nums1, int[] nums2) {
        Stack<Integer> iStack = new Stack<Integer>();
        Map<Integer, Integer> iIMap = new HashMap<Integer, Integer>();

        for (int i : nums2) {
            while (!iStack.isEmpty() && iStack.peek() < i) {
                iIMap.put(iStack.pop(), i);
            }

            iStack.add(i);
        }

        for (int i = 0; i < nums1.length; i++) {
            if (iIMap.containsKey(nums1[i])) {
                nums1[i] = iIMap.get(nums1[i]);
            } else {
                nums1[i] = -1;
            }
        }

        return nums1;
    }
}