下一个更大元素II-栈503-python

循环数组的单调栈问题，可以通过两倍数组长度+取余操作模拟循环数组。

class Solution:
    def nextGreaterElements(self, nums: List[int]) -> List[int]:
        n = len(nums)
        stack = []
        res = [0] * n

        for i in range(2*n-1, -1, -1):
            pos = i % n
            while stack and stack[-1] <= nums[pos]:
                stack.pop()
            if not stack:
                res[pos] = -1
            else:
                res[pos] = stack[-1]
            stack.append(nums[pos])

        return res