633. Sum of Square Numbers

def judgeSquareSum(self, c):
        """
        :type c: int
        :rtype: bool
        """
        l, r = 0, int(c ** 0.5)
        while l <= r:
            s = l ** 2 + r ** 2
            if s == c:
                return True
            elif s < c:
                l += 1
            else:
                r -= 1
        return False