【蓝桥杯】790. 数的三次方根*（二分）

穿越隧道

#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;
const int N = 1e5 + 10;
const double ep = 1e-8;
double n;
int main(){
	scanf("%lf",&n);
	double l = -10000, r = 10000;//关键在于lr的初始值，因答案可能为负数
	while(l < r){
		double mid = (l + r)/2;
		if(abs(mid * mid * mid - n) <= ep){
			printf("%.6f",mid);
			break;
		}
		if(mid * mid * mid > n){
			r = mid;
		}
		else if(mid*mid*mid < n){
			l = mid;
		}
	}
	return 0;
}