每日一题：链表中的下一个更大节点

/**

 * Definition for singly-linked list.

 * public class ListNode {

 *     int val;

 *     ListNode next;

 *     ListNode() {}

 *     ListNode(int val) { this.val = val; }

 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }

 * }

 */

class Solution {

    public int[] nextLargerNodes(ListNode head) {

        ListNode ass = head;

        List<Integer> list = new ArrayList<>();

        while (ass != null) {

            list.add(ass.val);

            ass = ass.next;

        }

        int n = list.size();

        int[] ret = new int[n];

        // 单调栈，非递增

        Stack<Integer> stack = new Stack<>();

        for (int i = 0; i < n; ++i) {

            while (!stack.isEmpty() && list.get(stack.peek()) < list.get(i)) {

                // 出栈

                int j = stack.pop();

                ret[j] = list.get(i);

            }

            // 入栈

            stack.push(i);

        }

        return ret;

    }

}