题目描述

blablabla

样例

#include<iostream>
#include<iomanip>
using namespace std;

int main(){
    double n; cin >> n;
    double pre_x = 2;
    double e = 1e-7;
    double x = 1;
    while(x-pre_x>e||pre_x-x>e){
       pre_x = x;
       x = x - (x*x*x-n)/(2*x*x);
    }
    cout<<fixed<<setprecision(6)<<x;
    return 0;
}