6.数的三次方根

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 int main () {
 4     double n;
 5     cin >> n;
 6     double l = -100, r = 100;
 7     while (r - l > 1e-8) { //当区间足够小的时候 
 8         double mid = (l + r) / 2;
 9         if (mid * mid * mid >= n) {
10             r = mid;
11         } else {
12             l = mid;
13         }
14     }
15     cout << fixed << setprecision(6) << l << endl;
16     return 0;
17 }