题解 | #求解立方根#

import sys

def cube_root(x, epsilon=0.001, max_iterations=100):
    if x == 0:
        return 0

    guess = x / 3  # 初始猜测值为 x/3
    
    for _ in range(max_iterations):
        next_guess = (2 * guess + x / (guess * guess)) / 3  # 二次迭代法公式
        if abs(next_guess - guess) < epsilon:
            return round(next_guess,1)
        guess = next_guess

    return round(guess,1)


for line in sys.stdin:
    a = line.rstrip()
    print(cube_root(float(a)))

有待研究，下面两种时间效率不够。

def cube_root(x, epsilon=0.0001):if x == 0:return 0

import sys


def cube_root(x, epsilon=0.01):
    if x == 0:
        return 0

    low = 0
    high = max(1, x)
    guess = (low + high) / 2

    while abs(guess ** 3 - x) > epsilon:
        if guess ** 3 < x:
            low = guess
        else:
            high = guess
        guess = (low + high) / 2

    return round(guess,1)


for line in sys.stdin:
    a = line.rstrip()
    print(cube_root(float(a)))
############################

import sys


def cube_root(x, epsilon=0.01):
    low = 0
    high = x
    guess = (low + high) / 2

    while abs(guess ** 3 - x) > epsilon:
        if guess ** 3 < x:
            low = guess
        else:
            high = guess
        guess = (low + high) / 2

    return round(guess,1)


for line in sys.stdin:
    a = line.rstrip()
    print(cube_root(float(a)))