二分法分情况讨论

#include <iostream>
#include <algorithm>
using namespace std;

int main() {
    double num = 0;
    cin >> num;
    double t = num;
    int sign = 1;
    if (num == 0 || num == 1) {
        printf("%.1f", num);
        return 0;
    }
    if (num < 0) {
        num = abs(num);
        sign = -1;
    }
    double left = 0, right = 0;
    if (num < 1) {
        left = 0;
        right = 1;
    }
    else {
        left = 1;
        right = num;
    }
    double mid = left + (right - left) / 2.0;
    while (abs(mid*mid*mid - num) > 0.001) {
        if (mid*mid*mid < num) left = mid;
        else right = mid;
        mid = left + (right - left) / 2.0;
    }
    printf("%.1f", sign * mid);
    return 0;
}