C++ 代码

#include<iostream>
using namespace std;
int main()
{
    double n,down=-1e4,up=1e4,mid;
    scanf("%lf",&n);
    while(up-down>1e-8){
        mid=(down+up)/2;
        if(mid*mid*mid>=n)up=mid;
        else down=mid;
    }
    printf("%lf\n",down);
    return 0;
}