27行代码,为什么要有res=mid,不明白
#include<iostream>
#include<iomanip>
#include<cmath>
using namespace std;
#define double long double
const double eps = 1e-12;
int main()
{
int T = 1;
cin >> T;
while (T--)
{
double n;
cin >> n;
double l = 0, r = 100000, res = 0;
while (l <= r) //二分法查找答案
{
double mid = (l + r) / 2;
if (fabs(mid * mid * mid - n) <= eps)//满足精度
{
res = mid;
break;
}
if (mid * mid * mid > n)
r = mid - 0.0001;
else if (mid * mid * mid < n)
l = mid + 0.0001,res=mid; //当满足条件不满足精度时返回一个近似值(为什么res=mid)
}
cout << setprecision(3) << fixed << res << endl; //setprecision(3)函数用来保留有效数字,fixed用来防止浮点数科学计数法
}
return 0;
}