Leetcode 496. Next Greater Element I

单调栈的应用.

class Solution:
    def nextGreaterElement(self, nums1: List[int], nums2: List[int]) -> List[int]:
        next = []
        stack = []
        for i in range(len(nums2)):
            while stack and stack[-1][1] < nums2[i]:
                next[stack.pop()[0]] = nums2[i]
            stack.append((i, nums2[i]))
            next.append(-1)
        ret = []
        for val in nums1:
            ret.append(next[nums2.index(val)])
        return ret