Next Greater Element Circular

next_greater_element_circular.py

def nextGreaterElement(array):
    if not array: return []
	n = len(array)
	if n == 1:
		return [-1]
	stack = []
	result = [-1 for _ in range(n)]
	# fill next greater values - non circular, from stack
	for long_idx in range(2*n):
		idx = long_idx%n
		num = array[idx]
		while stack and array[stack[-1]] < num:
			result[stack.pop()] = array[idx]
		stack += [idx]
	# print("stack", stack)
	stack.clear()
	return result