题目：

题解：

class Solution {public int[] nextGreaterElement(int[] nums1, int[] nums2) {Map<Integer, Integer> map = new HashMap<Integer, Integer>();Deque<Integer> stack = new ArrayDeque<Integer>();for (int i = nums2.length - 1; i >= 0; --i) {int num = nums2[i];while (!stack.isEmpty() && num >= stack.peek()) {stack.pop();}map.put(num, stack.isEmpty() ? -1 : stack.peek());stack.push(num);}int[] res = new int[nums1.length];for (int i = 0; i < nums1.length; ++i) {res[i] = map.get(nums1[i]);}return res;}
}