def NextSmallerNumber(a):
    if a is None:
        return None

    n = len(a)
    result = [-1] * n
    stack = []

    for i in range(n - 1, -1, -1):
        while stack and stack[-1] >= a[i]:
            stack.pop()

        if stack:
            result[i] = stack[-1]

        stack.append(a[i])

    return result


Python 3✅

Sum of digital
Python 3✅

Who have Tech M Exam Guys  on 23rd July 2023