https://leetcode-cn.com/problems/daily-temperatures/

单调栈

https://www.yuque.com/docs/share/dcdb944b-0f51-4f7b-a14b-b847ed7bad65?# 《单调栈及其更新结构》

 //单调栈解法
    public int[] dailyTemperatures(int[] temperatures) {
        if (temperatures == null || temperatures.length == 0) {
            return new int[0];
        }
        int N = temperatures.length;
        int[] ans = new int[N];
        // 求一个数右边最近的比它大的数， 那么栈底到栈顶就从大到小, 栈里放的是下标
        Stack<List<Integer>> stack = new Stack<>();
        for (int i = 0; i < temperatures.length; i++) {
            while (!stack.isEmpty() && temperatures[i] > temperatures[stack.peek().get(0)]) {
                List<Integer> pop = stack.pop();
                for (Integer popi : pop) {
                    ans[popi] = i - popi;
                }
            }
            if (!stack.isEmpty() && temperatures[stack.peek().get(0)] == temperatures[i]) {
                stack.peek().add(i);
            } else {
                ArrayList<Integer> list = new ArrayList<>();
                list.add(i);
                stack.push(list);
            }
        }
        return ans;
    }