static double g32(double n){ //简易版double i = 0, k = 0.0005f;if (n < 0) {    //输入负数判断k /= -1;}do{i+=k;}while(abs(i*i*i)<abs(n)); //abs为自己写的求绝对值方法return i;}

    static double g33(double n){    //优化2double i = 0, k = 5f;if (n < 0) {k /= -1;}for (int t = 0; t < 15; t++) {//精度到小数点后15位do {i += k;　　//开始时每次加5快速逼近正确值} while (abs(i * i * i) < abs(n));　　//当i^3>=n时退出i-=k;k /= 9.2;　　//i还原到退出前的值,k缩小,进入下一次逼近}　return i;}

    static double g34(double n){    //最终优化double i = 0, k = 5f;if (n < 0) {k /= -1;}int w=0;for (int t = 0; t < 15; t++) {do {i += k;k=k+w*k/50000;w++;　　//循环计数器} while (abs(i * i * i) < abs(n));i-=k;k /= 9.5;}System.out.println(w);return i;}

package com.gfuzan.test;import java.util.Scanner;public class Test {/*** 开发: GFuZan* 时间: 2017.08.08* 功能: 立方根*/public static void main(String[] args) {System.out.print("请输入一个数: ");Scanner sc = new Scanner(System.in);double n = sc.nextDouble();sc.close();System.out.println("Math:    \t"+ Math.pow(n, 1.0/3));System.out.println("My简易版:  \t"+g32(n)); System.out.println("My优化2:  \t"+g33(n)); System.out.println("My最终优化:\t"+g34(n)); }static double g32(double n){ //简易版double i = 0, k = 0.0005f;if (n < 0) {k /= -1;}do{i+=k;}while(abs(i*i*i)<abs(n));return i;}static double g34(double n){    //最终优化double i = 0, k = 5f;if (n < 0) {k /= -1;}int w=0;for (int t = 0; t < 15; t++) {do {i += k;k=k+w*k/50000;w++;} while (abs(i * i * i) < abs(n));i-=k;k /= 9.5;}return i;}static double g33(double n){    //优化2double i = 0, k = 5f;if (n < 0) {k /= -1;}for (int t = 0; t < 15; t++) {do {i += k;} while (abs(i * i * i) < abs(n));i-=k;k /= 9.2;}return i;}static double abs(double f) {if (f < 0) {return 0 - f;}return f;}
}