496. 下一个更大元素 I

496. 下一个更大元素 I

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