Convex Polygon Python Solution with Tests

lcpy gen -n 469   # by problem number
lcpy gen -s convex_polygon   # by problem name

Input: points = [[0,0],[0,5],[5,5],[5,0]]
Output: true

Input: points = [[0,0],[0,10],[10,10],[10,0],[5,5]]
Output: false

class Solution:
    # Time: O(n)
    # Space: O(1)
    def is_convex(self, points: list[list[int]]) -> bool:
        n = len(points)
        sign = 0
        for i in range(n):
            x1, y1 = points[i]
            x2, y2 = points[(i + 1) % n]
            x3, y3 = points[(i + 2) % n]
            cross = (x2 - x1) * (y3 - y2) - (y2 - y1) * (x3 - x2)
            if cross != 0:
                if sign == 0:
                    sign = 1 if cross > 0 else -1
                elif (cross > 0) != (sign > 0):
                    return False
        return True