Next Greater Element Using a Stack

greatest_right_number.py

from Stack import MyStack

def next_greater_element(lst):
    # Write your code here
    s = MyStack()
    ln = len(lst)
    for idx in range(ln-1, -1, -1):
        num = lst[idx]
        while not s.is_empty() and s.top() <= num:
            s.pop()
        lst[idx] = s.top() if s.top() else -1
        s.push(num)
    return lst