Bitcoin 程式設計

class Point:
    def __init__(self, x, y, a, b):
        self.a = a
        self.b = b
        self.x = x
        self.y = y
        # 驗證點在曲線上: y² = x³ + ax + b
        if self.x is not None and self.y is not None:
            if self.y**2 != self.x**3 + a*x + b:
                raise ValueError(f'({x}, {y}) is not on the curve')

    def __add__(self, other):
        # 點加法實現
        if self.x is None:
            return other
        if other.x is None:
            return self
        # ... 完整實現見書中