Skip to content

Example: Binary Search Float⚓︎

code

Description⚓︎

Given a floating point number \(n\), find its cubic root.

Input format⚓︎

One line containing a floating point number \(n\).

Output format⚓︎

A single line containing a floating point number representing the solution to the problem.

Note that the result is preserved to \(6\) decimal places.

Data range⚓︎

\(-10000 \leqslant n \leqslant 10000\)

Solution⚓︎

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
#include <iostream>
using namespace std;

double x;

int main() {
    cin >> x;
    double l = -1000, r = 1000;

    // we can also execute "for" loop for 100 times
    while (r - l >= 1e-8) {
        double mid = (l + r) / 2;
        if (mid * mid * mid <= x) l = mid;
        else r = mid;
    }
    printf("%.6lf", l);
    return 0;
}